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Author name code: mclaughlin
ADS astronomy entries on 2022-09-14
author:"McLaughlin, James A."
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Title: Observations of Instability-driven Nanojets in Coronal Loops
Authors: Sukarmadji, A. Ramada C.; Antolin, Patrick; McLaughlin,
James A.
2022ApJ...934..190S Altcode: 2022arXiv220210960S
The recent discovery of nanojets by Antolin et al. represents
magnetic reconnection in a braided field, thus clearly identifying
reconnection-driven nanoflares. Due to their small scale (500 km
in width, 1500 km in length) and short timescales (<15 s), it is
unclear how pervasive nanojets are in the solar corona. In this paper,
we present Interface Region Imaging Spectrograph and Solar Dynamics
Observatory observations of nanojets found in multiple coronal
structures, namely, in a coronal loop powered by a blowout jet,
and in two other coronal loops with coronal rain. In agreement with
previous findings, we observe that nanojets are accompanied by small
nanoflare-like intensity bursts in the (E)UV, have velocities of 150-250
km s<SUP>-1</SUP> and occur transversely to the field line of origin,
which is sometimes observed to split. However, we find a variety of
nanojet directions in the plane transverse to the loop axis. These
nanojets are found to have kinetic and thermal energies within the
nanoflare range, and often occur in clusters. In the blowout jet case
study, the Kelvin-Helmholtz instability (KHI) is directly identified
as the reconnection driver. For the other two loops, we find that
both, KHI and Rayleigh-Taylor instability (RTI) are likely to be the
drivers. However, we find that KHI and RTI are each more likely in one
of the other two cases. These observations of nanojets in a variety
of structures and environments support nanojets being a general result
of reconnection that are driven here by dynamic instabilities.
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Title: The Independence of Oscillatory Reconnection Periodicity from
the Initial Pulse
Authors: Karampelas, Konstantinos; McLaughlin, James A.; Botha,
Gert J. J.; Régnier, Stéphane
2022ApJ...933..142K Altcode: 2022arXiv220701980K
Oscillatory reconnection can manifest through the interaction between
the ubiquitous MHD waves and omnipresent null points in the solar
atmosphere and is characterized by an inherent periodicity. In the
current study, we focus on the relationship between the period
of oscillatory reconnection and the strength of the wave pulse
initially perturbing the null point, in a hot coronal plasma. We
use the PLUTO code to solve the fully compressive, resistive MHD
equations for a 2D magnetic X-point. Using wave pulses with a wide
range of amplitudes, we perform a parameter study to obtain values
for the period, considering the presence and absence of anisotropic
thermal conduction separately. In both cases, we find that the
resulting period is independent of the strength of the initial
perturbation. The addition of anisotropic thermal conduction only
leads to an increase in the mean value for the period, in agreement
with our previous study. We also consider a different type of initial
driver and we obtain an oscillation period matching the independent
trend previously mentioned. Thus, we report for the first time on
the independence between the type and strength of the initializing
wave pulse and the resulting period of oscillatory reconnection in a
hot coronal plasma. This makes oscillatory reconnection a promising
mechanism to be used within the context of coronal seismology.
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Title: Oscillatory Reconnection of a 2D X-point in a hot coronal
plasma
Authors: Karampelas, Konstantinos; Botha, Gert J. J.; Regnier,
Stephane; Mclaughlin, James A.
2022cosp...44.2559K Altcode:
Oscillatory reconnection (a relaxation mechanism with periodic changes
in connectivity) has been proposed as a potential physical mechanism
underpinning several periodic phenomena in the solar atmosphere
including, but not limited to, quasi-periodic pulsations (QPPs)
and flows. In the past, this mechanism had been extensively studied
numerically for 2D and 3D simulations of null points in cold plasma. In
our latest studies, we have expanded our understanding of oscillatory
reconnection, by considering for the first time hot, coronal plasma. We
will be presenting our latest results, from numerically solving the
fully-compressive, resistive MHD equations for a 2D magnetic X-point
under coronal conditions using the PLUTO code. We report on the
resulting oscillatory reconnection including its periodicity and decay
rate, by tracking the evolution of the current density profile at the
null point. We also consider, for the first time, the effect of adding
anisotropic thermal conduction to the mechanism, and how it simplifies
the spectrum of the oscillation profile and increases its decay rate,
while still allowing the mechanism to manifest. Finally, we reveal how
the equilibrium magnetic field strength, density distribution and the
amplitude of the initial perturbation relate to the decay rate, and
period of oscillatory reconnection, opening the tantalising possibility
of utilizing oscillatory reconnection as a seismological tool.
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Title: Using Oscillatory Reconnection of a 2D X-point as a tool for
coronal seismology.
Authors: Karampelas, Konstantinos; Botha, Gert J. J.; Regnier,
Stephane; Mclaughlin, James A.
2022cosp...44.2487K Altcode:
The mechanism of oscillatory reconnection of a null point has been
one of the proposed mechanisms behind phenomena like quasi-periodic
pulsations (QPPs). The manifestation of this mechanism through the
interaction of the ubiquitous waves with null points in the solar
atmosphere opens the possibility of utilizing oscillatory reconnection
as a tool for coronal seismology. In the past, the first steps had
been taken, by connecting the length of the initial current sheet
with the period of oscillatory reconnection, and by identifying a
linear regime where the period is affected by resistivity. Our recent
numerical studies have expanded upon these findings, by considering
plasma at coronal conditions, with the addition of anisotropic
thermal conduction. We have performed a series of parameter studies
with the use of the PLUTO code, which reveal a relation between the
equilibrium magnetic field strength and density distribution with
the period and decay rate of oscillatory reconnection. In addition,
we see an independence of the oscillation period from the type and
strength of the external wave pulse, which perturbs the null from its
initial equilibrium state. This allows us to formulate an empirical
formula connecting these four quantities, opening the way in using
oscillatory reconnection for coronal seismology.
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Title: First Dark Matter Search Results from the LUX-ZEPLIN (LZ)
Experiment
Authors: Aalbers, J.; Akerib, D. S.; Akerlof, C. W.; Al Musalhi,
A. K.; Alder, F.; Alqahtani, A.; Alsum, S. K.; Amarasinghe, C. S.;
Ames, A.; Anderson, T. J.; Angelides, N.; Araújo, H. M.; Armstrong,
J. E.; Arthurs, M.; Azadi, S.; Bailey, A. J.; Baker, A.; Balajthy, J.;
Balashov, S.; Bang, J.; Bargemann, J. W.; Barry, M. J.; Barthel, J.;
Bauer, D.; Baxter, A.; Beattie, K.; Belle, J.; Beltrame, P.; Bensinger,
J.; Benson, T.; Bernard, E. P.; Bhatti, A.; Biekert, A.; Biesiadzinski,
T. P.; Birch, H. J.; Birrittella, B.; Blockinger, G. M.; Boast, K. E.;
Boxer, B.; Bramante, R.; Brew, C. A. J.; Brás, P.; Buckley, J. H.;
Bugaev, V. V.; Burdin, S.; Busenitz, J. K.; Buuck, M.; Cabrita, R.;
Carels, C.; Carlsmith, D. L.; Carlson, B.; Carmona-Benitez, M. C.;
Cascella, M.; Chan, C.; Chawla, A.; Chen, H.; Cherwinka, J. J.; Chott,
N. I.; Cole, A.; Coleman, J.; Converse, M. V.; Cottle, A.; Cox, G.;
Craddock, W. W.; Creaner, O.; Curran, D.; Currie, A.; Cutter, J. E.;
Dahl, C. E.; David, A.; Davis, J.; Davison, T. J. R.; Delgaudio, J.;
Dey, S.; de Viveiros, L.; Dobi, A.; Dobson, J. E. Y.; Druszkiewicz,
E.; Dushkin, A.; Edberg, T. K.; Edwards, W. R.; Elnimr, M. M.; Emmet,
W. T.; Eriksen, S. R.; Faham, C. H.; Fan, A.; Fayer, S.; Fearon,
N. M.; Fiorucci, S.; Flaecher, H.; Ford, P.; Francis, V. B.; Fraser,
E. D.; Fruth, T.; Gaitskell, R. J.; Gantos, N. J.; Garcia, D.; Geffre,
A.; Gehman, V. M.; Genovesi, J.; Ghag, C.; Gibbons, R.; Gibson, E.;
Gilchriese, M. G. D.; Gokhale, S.; Gomber, B.; Green, J.; Greenall,
A.; Greenwood, S.; van der Grinten, M. G. D.; Gwilliam, C. B.; Hall,
C. R.; Hans, S.; Hanzel, K.; Harrison, A.; Hartigan-O'Connor, E.;
Haselschwardt, S. J.; Hertel, S. A.; Heuermann, G.; Hjemfelt, C.; Hoff,
M. D.; Holtom, E.; Y-K. Hor, J.; Horn, M.; Huang, D. Q.; Hunt, D.;
Ignarra, C. M.; Jacobsen, R. G.; Jahangir, O.; James, R. S.; Jeffery,
S. N.; Ji, W.; Johnson, J.; Kaboth, A. C.; Kamaha, A. C.; Kamdin, K.;
Kasey, V.; Kazkaz, K.; Keefner, J.; Khaitan, D.; Khaleeq, M.; Khazov,
A.; Khurana, I.; Kim, Y. D.; Kocher, C. D.; Kodroff, D.; Korley, L.;
Korolkova, E. V.; Kras, J.; Kraus, H.; Kravitz, S.; Krebs, H. J.;
Kreczko, L.; Krikler, B.; Kudryavtsev, V. A.; Kyre, S.; Landerud, B.;
Leason, E. A.; Lee, C.; Lee, J.; Leonard, D. S.; Leonard, R.; Lesko,
K. T.; Levy, C.; Li, J.; Liao, F. -T.; Liao, J.; Lin, J.; Lindote, A.;
Linehan, R.; Lippincott, W. H.; Liu, R.; Liu, X.; Liu, Y.; Loniewski,
C.; Lopes, M. I.; Lopez Asamar, E.; López Paredes, B.; Lorenzon, W.;
Lucero, D.; Luitz, S.; Lyle, J. M.; Majewski, P. A.; Makkinje, J.;
Malling, D. C.; Manalaysay, A.; Manenti, L.; Mannino, R. L.; Marangou,
N.; Marzioni, M. F.; Maupin, C.; McCarthy, M. E.; McConnell, C. T.;
McKinsey, D. N.; McLaughlin, J.; Meng, Y.; Migneault, J.; Miller,
E. H.; Mizrachi, E.; Mock, J. A.; Monte, A.; Monzani, M. E.; Morad,
J. A.; Morales Mendoza, J. D.; Morrison, E.; Mount, B. J.; Murdy,
M.; Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.; Nehrkorn,
C.; Nelson, H. N.; Neves, F.; Nguyen, A.; Nikoleyczik, J. A.; Nilima,
A.; O'Dell, J.; O'Neill, F. G.; O'Sullivan, K.; Olcina, I.; Olevitch,
M. A.; Oliver-Mallory, K. C.; Orpwood, J.; Pagenkopf, D.; Pal, S.;
Palladino, K. J.; Palmer, J.; Pangilinan, M.; Parveen, N.; Patton,
S. J.; Pease, E. K.; Penning, B.; Pereira, C.; Pereira, G.; Perry,
E.; Pershing, T.; Peterson, I. B.; Piepke, A.; Podczerwinski, J.;
Porzio, D.; Powell, S.; Preece, R. M.; Pushkin, K.; Qie, Y.; Ratcliff,
B. N.; Reichenbacher, J.; Reichhart, L.; Rhyne, C. A.; Richards, A.;
Riffard, Q.; Rischbieter, G. R. C.; Rodrigues, J. P.; Rodriguez, A.;
Rose, H. J.; Rosero, R.; Rossiter, P.; Rushton, T.; Rutherford, G.;
Rynders, D.; Saba, J. S.; Santone, D.; Sazzad, A. B. M. R.; Schnee,
R. W.; Scovell, P. R.; Seymour, D.; Shaw, S.; Shutt, T.; Silk, J. J.;
Silva, C.; Sinev, G.; Skarpaas, K.; Skulski, W.; Smith, R.; Solmaz,
M.; Solovov, V. N.; Sorensen, P.; Soria, J.; Stancu, I.; Stark, M. R.;
Stevens, A.; Stiegler, T. M.; Stifter, K.; Studley, R.; Suerfu, B.;
Sumner, T. J.; Sutcliffe, P.; Swanson, N.; Szydagis, M.; Tan, M.;
Taylor, D. J.; Taylor, R.; Taylor, W. C.; Temples, D. J.; Tennyson,
B. P.; Terman, P. A.; Thomas, K. J.; Tiedt, D. R.; Timalsina, M.; To,
W. H.; Tomás, A.; Tong, Z.; Tovey, D. R.; Tranter, J.; Trask, M.;
Tripathi, M.; Tronstad, D. R.; Tull, C. E.; Turner, W.; Tvrznikova,
L.; Utku, U.; Va'vra, J.; Vacheret, A.; Vaitkus, A. C.; Verbus, J. R.;
Voirin, E.; Waldron, W. L.; Wang, A.; Wang, B.; Wang, J. J.; Wang,
W.; Wang, Y.; Watson, J. R.; Webb, R. C.; White, A.; White, D. T.;
White, J. T.; White, R. G.; Whitis, T. J.; Williams, M.; Wisniewski,
W. J.; Witherell, M. S.; Wolfs, F. L. H.; Wolfs, J. D.; Woodford, S.;
Woodward, D.; Worm, S. D.; Wright, C. J.; Xia, Q.; Xiang, X.; Xiao,
Q.; Xu, J.; Yeh, M.; Yin, J.; Young, I.; Zarzhitsky, P.; Zuckerman,
A.; Zweig, E. A.
2022arXiv220703764A Altcode:
The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on
a dual-phase xenon time projection chamber operating at the Sanford
Underground Research Facility in Lead, South Dakota, USA. This Letter
reports results from LZ's first search for Weakly Interacting Massive
Particles (WIMPs) with an exposure of 60 live days using a fiducial
mass of 5.5 t. A profile-likelihood ratio analysis shows the data to
be consistent with a background-only hypothesis, setting new limits
on spin-independent WIMP-nucleon, spin-dependent WIMP-neutron, and
spin-dependent WIMP-proton cross-sections for WIMP masses above 9
GeV/c$^2$. The most stringent limit is set at 30 GeV/c$^2$, excluding
cross sections above 5.9$\times 10^{-48}$ cm$^2$ at the 90\% confidence
level.
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Title: Cosmogenic production of <SUP>37</SUP>Ar in the context of
the LUX-ZEPLIN experiment
Authors: Aalbers, J.; Akerib, D. S.; Al Musalhi, A. K.; Alder, F.;
Alsum, S. K.; Amarasinghe, C. S.; Ames, A.; Anderson, T. J.; Angelides,
N.; Araújo, H. M.; Armstrong, J. E.; Arthurs, M.; Bai, X.; Baker,
A.; Balajthy, J.; Balashov, S.; Bang, J.; Bargemann, J. W.; Bauer,
D.; Baxter, A.; Beattie, K.; Bernard, E. P.; Bhatti, A.; Biekert, A.;
Biesiadzinski, T. P.; Birch, H. J.; Blockinger, G. M.; Bodnia, E.;
Boxer, B.; Brew, C. A. J.; Brás, P.; Burdin, S.; Busenitz, J. K.;
Buuck, M.; Cabrita, R.; Carmona-Benitez, M. C.; Cascella, M.; Chan,
C.; Chawla, A.; Chen, H.; Chott, N. I.; Cole, A.; Converse, M. V.;
Cottle, A.; Cox, G.; Creaner, O.; Cutter, J. E.; Dahl, C. E.; David,
A.; de Viveiros, L.; Dobson, J. E. Y.; Druszkiewicz, E.; Eriksen,
S. R.; Fan, A.; Fayer, S.; Fearon, N. M.; Fiorucci, S.; Flaecher,
H.; Fraser, E. D.; Fruth, T.; Gaitskell, R. J.; Genovesi, J.; Ghag,
C.; Gibson, E.; Gilchriese, M. G. D.; Gokhale, S.; van der Grinten,
M. G. D.; Gwilliam, C. B.; Hall, C. R.; Haselschwardt, S. J.; Hertel,
S. A.; Horn, M.; Huang, D. Q.; Hunt, D.; Ignarra, C. M.; Jahangir,
O.; James, R. S.; Ji, W.; Johnson, J.; Kaboth, A. C.; Kamaha, A. C.;
Kamdin, K.; Khaitan, D.; Khazov, A.; Khurana, I.; Kodroff, D.; Korley,
L.; Korolkova, E. V.; Kraus, H.; Kravitz, S.; Kreczko, L.; Kudryavtsev,
V. A.; Leason, E. A.; Leonard, D. S.; Lesko, K. T.; Levy, C.; Lee,
J.; Lin, J.; Lindote, A.; Linehan, R.; Lippincott, W. H.; Liu, X.;
Lopes, M. I.; Lopez Asamar, E.; Lopez-Paredes, B.; Lorenzon, W.;
Luitz, S.; Majewski, P. A.; Manalaysay, A.; Manenti, L.; Mannino,
R. L.; Marangou, N.; McCarthy, M. E.; McKinsey, D. N.; McLaughlin,
J.; Miller, E. H.; Mizrachi, E.; Monte, A.; Monzani, M. E.; Morad,
J. A.; Morales Mendoza, J. D.; Morrison, E.; Mount, B. J.; Murphy,
A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.; Nelson, H. N.; Neves, F.;
Nikoleyczik, J. A.; Nilima, A.; Olcina, I.; Oliver-Mallory, K.; Pal,
S.; Palladino, K. J.; Palmer, J.; Parveen, N.; Patton, S. J.; Pease,
E. K.; Penning, B.; Pereira, G.; Perry, E.; Pershing, J.; Piepke, A.;
Porzio, D.; Qie, Y.; Reichenbacher, J.; Rhyne, C. A.; Richards, A.;
Riffard, Q.; Rischbieter, G. R. C.; Rosero, R.; Rossiter, P.; Rushton,
T.; Santone, D.; Sazzad, A. B. M. R.; Schnee, R. W.; Scovell, P. R.;
Shaw, S.; Shutt, T. A.; Silk, J. J.; Silva, C.; Sinev, G.; Smith,
R.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Soria, J.; Stancu, I.;
Stevens, A.; Stifter, K.; Suerfu, B.; Sumner, T. J.; Swanson, N.;
Szydagis, M.; Taylor, W. C.; Taylor, R.; Temples, D. J.; Terman,
P. A.; Tiedt, D. R.; Timalsina, M.; To, W. H.; Tong, Z.; Tovey,
D. R.; Trask, M.; Tripathi, M.; Tronstad, D. R.; Turner, W.; Utku,
U.; Vaitkus, A.; Wang, B.; Wang, Y.; Wang, J. J.; Wang, W.; Watson,
J. R.; Webb, R. C.; White, R. G.; Whitis, T. J.; Williams, M.; Wolfs,
F. L. H.; Woodford, S.; Woodward, D.; Wright, C. J.; Xia, Q.; Xiang,
X.; Xu, J.; Yeh, M.; Lux-Zeplin Collaboration
2022PhRvD.105h2004A Altcode: 2022arXiv220102858A
We estimate the amount of <SUP>37</SUP>Ar produced in natural xenon
via cosmic-ray-induced spallation, an inevitable consequence of the
transportation and storage of xenon on the Earth's surface. We then
calculate the resulting <SUP>37</SUP>Ar concentration in a 10-tonne
payload (similar to that of the LUX-ZEPLIN experiment) assuming a
representative schedule of xenon purification, storage, and delivery
to the underground facility. Using the spallation model by Silberberg
and Tsao, the sea-level production rate of <SUP>37</SUP>Ar in natural
xenon is estimated to be 0.024 atoms /kg /day . Assuming the xenon is
successively purified to remove radioactive contaminants in 1-tonne
batches at a rate of 1 tonne /month , the average <SUP>37</SUP>Ar
activity after 10 tons are purified and transported underground is
0.058 −0.090 μ Bq /kg , depending on the degree of argon removal
during above-ground purification. Such cosmogenic <SUP>37</SUP>Ar
will appear as a noticeable background in the early science data,
while decaying with a 35-day half-life. This newly noticed production
mechanism of <SUP>37</SUP>Ar should be considered when planning for
future liquid-xenon-based experiments.
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Title: Novel Data Analysis Techniques in Coronal Seismology
Authors: Anfinogentov, Sergey A.; Antolin, Patrick; Inglis, Andrew
R.; Kolotkov, Dmitrii; Kupriyanova, Elena G.; McLaughlin, James A.;
Nisticò, Giuseppe; Pascoe, David J.; Krishna Prasad, S.; Yuan, Ding
2022SSRv..218....9A Altcode: 2021arXiv211213577A
We review novel data analysis techniques developed or adapted for
the field of coronal seismology. We focus on methods from the last
ten years that were developed for extreme ultraviolet (EUV) imaging
observations of the solar corona, as well as for light curves from
radio and X-ray. The review covers methods for the analysis of
transverse and longitudinal waves; spectral analysis of oscillatory
signals in time series; automated detection and processing of large
data sets; empirical mode decomposition; motion magnification;
and reliable detection, including the most common pitfalls causing
artefacts and false detections. We also consider techniques for the
detailed investigation of MHD waves and seismological inference of
physical parameters of the coronal plasma, including restoration of
the three-dimensional geometry of oscillating coronal loops, forward
modelling and Bayesian parameter inference.
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Title: A Next-Generation Liquid Xenon Observatory for Dark Matter
and Neutrino Physics
Authors: Aalbers, J.; Abe, K.; Aerne, V.; Agostini, F.; Maouloud,
S. Ahmed; Akerib, D. S.; Akimov, D. Yu.; Akshat, J.; Al Musalhi, A. K.;
Alder, F.; Alsum, S. K.; Althueser, L.; Amarasinghe, C. S.; Amaro,
F. D.; Ames, A.; Anderson, T. J.; Andrieu, B.; Angelides, N.; Angelino,
E.; Angevaare, J.; Antochi, V. C.; Antón Martin, D.; Antunovic, B.;
Aprile, E.; Araújo, H. M.; Armstrong, J. E.; Arneodo, F.; Arthurs,
M.; Asadi, P.; Baek, S.; Bai, X.; Bajpai, D.; Baker, A.; Balajthy, J.;
Balashov, S.; Balzer, M.; Bandyopadhyay, A.; Bang, J.; Barberio, E.;
Bargemann, J. W.; Baudis, L.; Bauer, D.; Baur, D.; Baxter, A.; Baxter,
A. L.; Bazyk, M.; Beattie, K.; Behrens, J.; Bell, N. F.; Bellagamba,
L.; Beltrame, P.; Benabderrahmane, M.; Bernard, E. P.; Bertone,
G. F.; Bhattacharjee, P.; Bhatti, A.; Biekert, A.; Biesiadzinski,
T. P.; Binau, A. R.; Biondi, R.; Biondi, Y.; Birch, H. J.; Bishara,
F.; Bismark, A.; Blanco, C.; Blockinger, G. M.; Bodnia, E.; Boehm,
C.; Bolozdynya, A. I.; Bolton, P. D.; Bottaro, S.; Bourgeois, C.;
Boxer, B.; Brás, P.; Breskin, A.; Breur, P. A.; Brew, C. A. J.;
Brod, J.; Brookes, E.; Brown, A.; Brown, E.; Bruenner, S.; Bruno,
G.; Budnik, R.; Bui, T. K.; Burdin, S.; Buse, S.; Busenitz, J. K.;
Buttazzo, D.; Buuck, M.; Buzulutskov, A.; Cabrita, R.; Cai, C.; Cai,
D.; Capelli, C.; Cardoso, J. M. R.; Carmona-Benitez, M. C.; Cascella,
M.; Catena, R.; Chakraborty, S.; Chan, C.; Chang, S.; Chauvin, A.;
Chawla, A.; Chen, H.; Chepel, V.; Chott, N. I.; Cichon, D.; Cimental
Chavez, A.; Cimmino, B.; Clark, M.; Co, R. T.; Colijn, A. P.; Conrad,
J.; Converse, M. V.; Costa, M.; Cottle, A.; Cox, G.; Creaner, O.;
Cuenca Garcia, J. J.; Cussonneau, J. P.; Cutter, J. E.; Dahl, C. E.;
D'Andrea, V.; David, A.; Decowski, M. P.; Dent, J. B.; Deppisch,
F. F.; de Viveiros, L.; Di Gangi, P.; Di Giovanni, A.; Di Pede, S.;
Dierle, J.; Diglio, S.; Dobson, J. E. Y.; Doerenkamp, M.; Douillet,
D.; Drexlin, G.; Druszkiewicz, E.; Dunsky, D.; Eitel, K.; Elykov, A.;
Emken, T.; Engel, R.; Eriksen, S. R.; Fairbairn, M.; Fan, A.; Fan,
J. J.; Farrell, S. J.; Fayer, S.; Fearon, N. M.; Ferella, A.; Ferrari,
C.; Fieguth, A.; Fieguth, A.; Fiorucci, S.; Fischer, H.; Flaecher,
H.; Flierman, M.; Florek, T.; Foot, R.; Fox, P. J.; Franceschini,
R.; Fraser, E. D.; Frenk, C. S.; Frohlich, S.; Fruth, T.; Fulgione,
W.; Fuselli, C.; Gaemers, P.; Gaior, R.; Gaitskell, R. J.; Galloway,
M.; Gao, F.; Garcia Garcia, I.; Genovesi, J.; Ghag, C.; Ghosh, S.;
Gibson, E.; Gil, W.; Giovagnoli, D.; Girard, F.; Glade-Beucke, R.;
Glück, F.; Gokhale, S.; de Gouvêa, A.; Gráf, L.; Grandi, L.; Grigat,
J.; Grinstein, B.; van der Grinten, M. G. D.; Grössle, R.; Guan, H.;
Guida, M.; Gumbsheimer, R.; Gwilliam, C. B.; Hall, C. R.; Hall, L. J.;
Hammann, R.; Han, K.; Hannen, V.; Hansmann-Menzemer, S.; Harata,
R.; Hardin, S. P.; Hardy, E.; Hardy, C. A.; Harigaya, K.; Harnik,
R.; Haselschwardt, S. J.; Hernandez, M.; Hertel, S. A.; Higuera,
A.; Hils, C.; Hochrein, S.; Hoetzsch, L.; Hoferichter, M.; Hood, N.;
Hooper, D.; Horn, M.; Howlett, J.; Huang, D. Q.; Huang, Y.; Hunt, D.;
Iacovacci, M.; Iaquaniello, G.; Ide, R.; Ignarra, C. M.; Iloglu, G.;
Itow, Y.; Jacquet, E.; Jahangir, O.; Jakob, J.; James, R. S.; Jansen,
A.; Ji, W.; Ji, X.; Joerg, F.; Johnson, J.; Joy, A.; Kaboth, A. C.;
Kamaha, A. C.; Kanezaki, K.; Kar, K.; Kara, M.; Kato, N.; Kavrigin,
P.; Kazama, S.; Keaveney, A. W.; Kellerer, J.; Khaitan, D.; Khazov,
A.; Khundzakishvili, G.; Khurana, I.; Kilminster, B.; Kleifges, M.;
Ko, P.; Kobayashi, M.; Kobayashi, M.; Kodroff, D.; Koltmann, G.;
Kopec, A.; Kopmann, A.; Kopp, J.; Korley, L.; Kornoukhov, V. N.;
Korolkova, E. V.; Kraus, H.; Krauss, L. M.; Kravitz, S.; Kreczko,
L.; Kudryavtsev, V. A.; Kuger, F.; Kumar, J.; López Paredes, B.;
LaCascio, L.; Laine, Q.; Landsman, H.; Lang, R. F.; Leason, E. A.;
Lee, J.; Leonard, D. S.; Lesko, K. T.; Levinson, L.; Levy, C.; Li,
I.; Li, S. C.; Li, T.; Liang, S.; Liebenthal, C. S.; Lin, J.; Lin,
Q.; Lindemann, S.; Lindner, M.; Lindote, A.; Linehan, R.; Lippincott,
W. H.; Liu, X.; Liu, K.; Liu, J.; Loizeau, J.; Lombardi, F.; Long,
J.; Lopes, M. I.; Lopez Asamar, E.; Lorenzon, W.; Lu, C.; Luitz, S.;
Ma, Y.; Machado, P. A. N.; Macolino, C.; Maeda, T.; Mahlstedt, J.;
Majewski, P. A.; Manalaysay, A.; Mancuso, A.; Manenti, L.; Manfredini,
A.; Mannino, R. L.; Marangou, N.; March-Russell, J.; Marignetti, F.;
Marrodán Undagoitia, T.; Martens, K.; Martin, R.; Martinez-Soler,
I.; Masbou, J.; Masson, D.; Masson, E.; Mastroianni, S.; Mastronardi,
M.; Matias-Lopes, J. A.; McCarthy, M. E.; McFadden, N.; McGinness,
E.; McKinsey, D. N.; McLaughlin, J.; McMichael, K.; Meinhardt, P.;
Menéndez, J.; Meng, Y.; Messina, M.; Midha, R.; Milisavljevic, D.;
Miller, E. H.; Milosevic, B.; Milutinovic, S.; Mitra, S. A.; Miuchi,
K.; Mizrachi, E.; Mizukoshi, K.; Molinario, A.; Monte, A.; Monteiro,
C. M. B.; Monzani, M. E.; Moore, J. S.; Morå, K.; Morad, J. A.;
Morales Mendoza, J. D.; Moriyama, S.; Morrison, E.; Morteau, E.;
Mosbacher, Y.; Mount, B. J.; Mueller, J.; Murphy, A. St. J.; Murra,
M.; Naim, D.; Nakamura, S.; Nash, E.; Navaieelavasani, N.; Naylor,
A.; Nedlik, C.; Nelson, H. N.; Neves, F.; Newstead, J. L.; Ni, K.;
Nikoleyczik, J. A.; Niro, V.; Oberlack, U. G.; Obradovic, M.; Odgers,
K.; O'Hare, C. A. J.; Oikonomou, P.; Olcina, I.; Oliver-Mallory, K.;
Oranday, A.; Orpwood, J.; Ostrovskiy, I.; Ozaki, K.; Paetsch, B.; Pal,
S.; Palacio, J.; Palladino, K. J.; Palmer, J.; Panci, P.; Pandurovic,
M.; Parlati, A.; Parveen, N.; Patton, S. J.; Pěč, V.; Pellegrini,
Q.; Penning, B.; Pereira, G.; Peres, R.; Perez-Gonzalez, Y.; Perry, E.;
Pershing, T.; Petrossian-Byrne, R.; Pienaar, J.; Piepke, A.; Pieramico,
G.; Pierre, M.; Piotter, M.; Pizella, V.; Plante, G.; Pollmann, T.;
Porzio, D.; Qi, J.; Qie, Y.; Qin, J.; Raj, N.; Rajado Silva, M.;
Ramanathan, K.; Ramírez García, D.; Ravanis, J.; Redard-Jacot, L.;
Redigolo, D.; Reichard, S.; Reichenbacher, J.; Rhyne, C. A.; Richards,
A.; Riffard, Q.; Rischbieter, G. R. C.; Rocchetti, A.; Rosenfeld,
S. L.; Rosero, R.; Rupp, N.; Rushton, T.; Saha, S.; Sanchez, L.;
Sanchez-Lucas, P.; Santone, D.; dos Santos, J. M. F.; Sarnoff,
I.; Sartorelli, G.; Sazzad, A. B. M. R.; Scheibelhut, M.; Schnee,
R. W.; Schrank, M.; Schreiner, J.; Schulte, P.; Schulte, D.; Schulze
Eissing, H.; Schumann, M.; Schwemberger, T.; Schwenk, A.; Schwetz,
T.; Scotto Lavina, L.; Scovell, P. R.; Sekiya, H.; Selvi, M.; Semenov,
E.; Semeria, F.; Shagin, P.; Shaw, S.; Shi, S.; Shockley, E.; Shutt,
T. A.; Si-Ahmed, R.; Silk, J. J.; Silva, C.; Silva, M. C.; Simgen, H.;
Šimkovic, F.; Sinev, G.; Singh, R.; Skulski, W.; Smirnov, J.; Smith,
R.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Soria, J.; Sparmann,
T. J.; Stancu, I.; Steidl, M.; Stevens, A.; Stifter, K.; Strigari,
L. E.; Subotic, D.; Suerfu, B.; Suliga, A. M.; Sumner, T. J.; Szabo,
P.; Szydagis, M.; Takeda, A.; Takeuchi, Y.; Tan, P. -L.; Taricco, C.;
Taylor, W. C.; Temples, D. J.; Terliuk, A.; Terman, P. A.; Thers,
D.; Thieme, K.; Thümmler, Th.; Tiedt, D. R.; Timalsina, M.; To,
W. H.; Toennies, F.; Tong, Z.; Toschi, F.; Tovey, D. R.; Tranter, J.;
Trask, M.; Trinchero, G. C.; Tripathi, M.; Tronstad, D. R.; Trotta,
R.; Tsai, Y. D.; Tunnell, C. D.; Turner, W. G.; Ueno, R.; Urquijo,
P.; Utku, U.; Vaitkus, A.; Valerius, K.; Vassilev, E.; Vecchi, S.;
Velan, V.; Vetter, S.; Vincent, A. C.; Vittorio, L.; Volta, G.;
von Krosigk, B.; von Piechowski, M.; Vorkapic, D.; Wagner, C. E. M.;
Wang, A. M.; Wang, B.; Wang, Y.; Wang, W.; Wang, J. J.; Wang, L. -T.;
Wang, M.; Wang, Y.; Watson, J. R.; Wei, Y.; Weinheimer, C.; Weisman,
E.; Weiss, M.; Wenz, D.; West, S. M.; Whitis, T. J.; Williams, M.;
Wilson, M. J.; Winkler, D.; Wittweg, C.; Wolf, J.; Wolf, T.; Wolfs,
F. L. H.; Woodford, S.; Woodward, D.; Wright, C. J.; Wu, V. H. S.;
Wu, P.; Wüstling, S.; Wurm, M.; Xia, Q.; Xiang, X.; Xing, Y.; Xu,
J.; Xu, Z.; Xu, D.; Yamashita, M.; Yamazaki, R.; Yan, H.; Yang, L.;
Yang, Y.; Ye, J.; Yeh, M.; Young, I.; Yu, H. B.; Yu, T. T.; Yuan, L.;
Zavattini, G.; Zerbo, S.; Zhang, Y.; Zhong, M.; Zhou, N.; Zhou, X.;
Zhu, T.; Zhu, Y.; Zhuang, Y.; Zopounidis, J. P.; Zuber, K.; Zupan, J.
2022arXiv220302309A Altcode:
The nature of dark matter and properties of neutrinos are among the
most pressing issues in contemporary particle physics. The dual-phase
xenon time-projection chamber is the leading technology to cover the
available parameter space for Weakly Interacting Massive Particles
(WIMPs), while featuring extensive sensitivity to many alternative dark
matter candidates. These detectors can also study neutrinos through
neutrinoless double-beta decay and through a variety of astrophysical
sources. A next-generation xenon-based detector will therefore be a true
multi-purpose observatory to significantly advance particle physics,
nuclear physics, astrophysics, solar physics, and cosmology. This
review article presents the science cases for such a detector.
---------------------------------------------------------
Title: Oscillatory Reconnection of a 2D X-point in a Hot Coronal
Plasma
Authors: Karampelas, Konstantinos; McLaughlin, James A.; Botha,
Gert J. J.; Régnier, Stéphane
2022ApJ...925..195K Altcode: 2021arXiv211205712K
Oscillatory reconnection (a relaxation mechanism with periodic changes
in connectivity) has been proposed as a potential physical mechanism
underpinning several periodic phenomena in the solar atmosphere,
including, but not limited to, quasi-periodic pulsations (QPPs). Despite
its importance, however, the mechanism has never been studied within
a hot, coronal plasma. We investigate oscillatory reconnection in a
one million Kelvin plasma by solving the fully-compressive, resistive
MHD equations for a 2D magnetic X-point under coronal conditions using
the PLUTO code. We report on the resulting oscillatory reconnection
including its periodicity and decay rate. We observe a more complicated
oscillating profile for the current density compared to that found for
a cold plasma, due to mode-conversion at the equipartition layer. We
also consider, for the first time, the effect of adding anisotropic
thermal conduction to the oscillatory reconnection mechanism, and
we find this simplifies the spectrum of the oscillation profile
and increases the decay rate. Crucially, the addition of thermal
conduction does not prevent the oscillatory reconnection mechanism
from manifesting. Finally, we reveal a relationship between the
equilibrium magnetic field strength, decay rate, and period of
oscillatory reconnection, which opens the tantalising possibility of
utilizing oscillatory reconnection as a seismological tool.
---------------------------------------------------------
Title: Is phase mixing important in the quiet Sun?
Authors: Morton, Richard; McLaughlin, James; Tiwari, Ajay; Van
Doorsselaere, Tom
2021AGUFMSH12B..09M Altcode:
The focus of many investigations on coronal wave heating has been to
scrutinise the role of transverse (i.e. kink) modes; examining their
damping by resonant absorption and the transfer of energy to Alfvén
modes. Subsequently, the Alfvén modes are then subject to phase
mixing and this leads to plasma heating. More recently, a non-linear
mechanism for energy transfer has also been proposed, the so called
uni-turbulence. Due to the ease with which they have been observed,
the rapidly damped standing kink modes in active regions have spawned
numerous studies investigating the role of resonant absorption in
the observed damping. However, their counterparts in the quiet Sun,
the propagating kink waves, have received little attention. Here I
will discuss the results from a large-scale study of kink wave damping
in the quiet Sun. We find convincing evidence that the damping of the
kink waves is significantly weaker than in active regions and suggests
that resonant absorption/phase mixing/uni-turbulence are not important
mechanisms for wave-based heating of the quiescent Sun. I will also
discuss the physical reason we suspect is behind this result and what
it tells us about the fine-scale structure of the quiescent corona.
---------------------------------------------------------
Title: Weak Damping of Propagating MHD Kink Waves in the Quiescent
Corona
Authors: Morton, Richard J.; Tiwari, Ajay K.; Van Doorsselaere, Tom;
McLaughlin, James A.
2021ApJ...923..225M Altcode: 2021arXiv210511924M
Propagating transverse waves are thought to be a key transporter of
Poynting flux throughout the Sun's atmosphere. Recent studies have shown
that these transverse motions, interpreted as the magnetohydrodynamic
kink mode, are prevalent throughout the corona. The associated energy
estimates suggest the waves carry enough energy to meet the demands
of coronal radiative losses in the quiescent Sun. However, it is still
unclear how the waves deposit their energy into the coronal plasma. We
present the results from a large-scale study of propagating kink waves
in the quiescent corona using data from the Coronal Multi-channel
Polarimeter (CoMP). The analysis reveals that the kink waves appear
to be weakly damped, which would imply low rates of energy transfer
from the large-scale transverse motions to smaller scales via either
uniturbulence or resonant absorption. This raises questions about how
the observed kink modes would deposit their energy into the coronal
plasma. Moreover, these observations, combined with the results of Monte
Carlo simulations, lead us to infer that the solar corona displays a
spectrum of density ratios, with a smaller density ratio (relative to
the ambient corona) in quiescent coronal loops and a higher density
ratio in active-region coronal loops.
---------------------------------------------------------
Title: Projected sensitivities of the LUX-ZEPLIN experiment to new
physics via low-energy electron recoils
Authors: Akerib, D. S.; Al Musalhi, A. K.; Alsum, S. K.; Amarasinghe,
C. S.; Ames, A.; Anderson, T. J.; Angelides, N.; Araújo, H. M.;
Armstrong, J. E.; Arthurs, M.; Bai, X.; Balajthy, J.; Balashov,
S.; Bang, J.; Bargemann, J. W.; Bauer, D.; Baxter, A.; Beltrame, P.;
Bernard, E. P.; Bernstein, A.; Bhatti, A.; Biekert, A.; Biesiadzinski,
T. P.; Birch, H. J.; Blockinger, G. M.; Bodnia, E.; Boxer, B.; Brew,
C. A. J.; Brás, P.; Burdin, S.; Busenitz, J. K.; Buuck, M.; Cabrita,
R.; Carmona-Benitez, M. C.; Cascella, M.; Chan, C.; Chott, N. I.;
Cole, A.; Converse, M. V.; Cottle, A.; Cox, G.; Creaner, O.; Cutter,
J. E.; Dahl, C. E.; de Viveiros, L.; Dobson, J. E. Y.; Druszkiewicz,
E.; Eriksen, S. R.; Fan, A.; Fayer, S.; Fearon, N. M.; Fiorucci, S.;
Flaecher, H.; Fraser, E. D.; Fruth, T.; Gaitskell, R. J.; Genovesi,
J.; Ghag, C.; Gibson, E.; Gokhale, S.; van der Grinten, M. G. D.;
Gwilliam, C. B.; Hall, C. R.; Hardy, C. A.; Haselschwardt, S. J.;
Hertel, S. A.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Jahangir,
O.; James, R. S.; Ji, W.; Johnson, J.; Kaboth, A. C.; Kamaha, A. C.;
Kamdin, K.; Kazkaz, K.; Khaitan, D.; Khazov, A.; Khurana, I.; Kodroff,
D.; Korley, L.; Korolkova, E. V.; Kraus, H.; Kravitz, S.; Kreczko,
L.; Krikler, B.; Kudryavtsev, V. A.; Leason, E. A.; Lee, J.; Leonard,
D. S.; Lesko, K. T.; Levy, C.; Li, J.; Liao, J.; Lindote, A.; Linehan,
R.; Lippincott, W. H.; Liu, X.; Lopes, M. I.; Lopez Asamar, E.; López
Paredes, B.; Lorenzon, W.; Luitz, S.; Majewski, P. A.; Manalaysay,
A.; Manenti, L.; Mannino, R. L.; Marangou, N.; McCarthy, M. E.;
McKinsey, D. N.; McLaughlin, J.; Miller, E. H.; Mizrachi, E.; Monte,
A.; Monzani, M. E.; Morad, J. A.; Morales Mendoza, J. D.; Morrison,
E.; Mount, B. J.; Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.;
Nelson, H. N.; Neves, F.; Nikoleyczik, J. A.; Nilima, A.; Nguyen, A.;
Olcina, I.; Oliver-Mallory, K. C.; Pal, S.; Palladino, K. J.; Palmer,
J.; Patton, S.; Parveen, N.; Pease, E. K.; Penning, B.; Pereira, G.;
Piepke, A.; Qie, Y.; Reichenbacher, J.; Rhyne, C. A.; Richards, A.;
Riffard, Q.; Rischbieter, G. R. C.; Rosero, R.; Rossiter, P.; Santone,
D.; Sazzad, A. B. M. R.; Schnee, R. W.; Scovell, P. R.; Shaw, S.;
Shutt, T. A.; Silk, J. J.; Silva, C.; Smith, R.; Solmaz, M.; Solovov,
V. N.; Sorensen, P.; Soria, J.; Stancu, I.; Stevens, A.; Stifter, K.;
Suerfu, B.; Sumner, T. J.; Swanson, N.; Szydagis, M.; Taylor, W. C.;
Taylor, R.; Temples, D. J.; Terman, P. A.; Tiedt, D. R.; Timalsina,
M.; To, W. H.; Tovey, D. R.; Tripathi, M.; Tronstad, D. R.; Turner,
W.; Utku, U.; Vaitkus, A.; Wang, B.; Wang, J. J.; Wang, W.; Watson,
J. R.; Webb, R. C.; White, R. G.; Whitis, T. J.; Williams, M.; Wolfs,
F. L. H.; Woodward, D.; Wright, C. J.; Xiang, X.; Xu, J.; Yeh, M.;
Zarzhitsky, P.
2021PhRvD.104i2009A Altcode: 2021arXiv210211740T
LUX-ZEPLIN is a dark matter detector expected to obtain world-leading
sensitivity to weakly-interacting massive particles interacting via
nuclear recoils with a ∼7 -tonne xenon target mass. This paper
presents sensitivity projections to several low-energy signals of the
complementary electron recoil signal type: 1) an effective neutrino
magnetic moment, and 2) an effective neutrino millicharge, both for
p p -chain solar neutrinos, 3) an axion flux generated by the Sun, 4)
axionlike particles forming the Galactic dark matter, 5) hidden photons,
6) mirror dark matter, and 7) leptophilic dark matter. World-leading
sensitivities are expected in each case, a result of the large 5.6 t
1000 d exposure and low expected rate of electron-recoil backgrounds
in the <100 keV energy regime. A consistent signal generation,
background model and profile-likelihood analysis framework is used
throughout.
---------------------------------------------------------
Title: A Statistical Study of Propagating MHD Kink Waves in the
Quiescent Corona
Authors: Tiwari, Ajay K.; Morton, Richard J.; McLaughlin, James A.
2021ApJ...919...74T Altcode: 2021arXiv210512451T
The Coronal Multi-channel Polarimeter (CoMP) has opened up exciting
opportunities to probe transverse MHD waves in the Sun's corona. The
archive of CoMP data is utilized to generate a catalog of quiescent
coronal loops that can be used for studying propagating kink waves. The
catalog contains 120 loops observed between 2012 and 2014. This catalog
is further used to undertake a statistical study of propagating kink
waves in the quiet regions of the solar corona, investigating phase
speeds, loop lengths, footpoint power ratio (a measure of wave power
entering the corona through each footpoint of a loop) and equilibrium
parameter (which provides a measure of the change in wave amplitude)
values. The statistical study enables us to establish the presence of a
relationship between the rate of damping and the length of the coronal
loop, with longer coronal loops displaying weaker wave damping. We
suggest the reason for this behavior is related to a decreasing average
density contrast between the loop and ambient plasma as loop length
increases. The catalog presented here will provide the community with
the foundation for the further study of propagating kink waves in the
quiet solar corona.
---------------------------------------------------------
Title: Magnetohydrodynamic Waves in Open Coronal Structures
Authors: Banerjee, D.; Krishna Prasad, S.; Pant, V.; McLaughlin, J. A.;
Antolin, P.; Magyar, N.; Ofman, L.; Tian, H.; Van Doorsselaere, T.;
De Moortel, I.; Wang, T. J.
2021SSRv..217...76B Altcode: 2020arXiv201208802B
Modern observatories have revealed the ubiquitous presence of
magnetohydrodynamic waves in the solar corona. The propagating waves
(in contrast to the standing waves) are usually originated in the lower
solar atmosphere which makes them particularly relevant to coronal
heating. Furthermore, open coronal structures are believed to be the
source regions of solar wind, therefore, the detection of MHD waves
in these structures is also pertinent to the acceleration of solar
wind. Besides, the advanced capabilities of the current generation
telescopes have allowed us to extract important coronal properties
through MHD seismology. The recent progress made in the detection,
origin, and damping of both propagating slow magnetoacoustic waves and
kink (Alfvénic) waves is presented in this review article especially
in the context of open coronal structures. Where appropriate, we give
an overview on associated theoretical modelling studies. A few of the
important seismological applications of these waves are discussed. The
possible role of Alfvénic waves in the acceleration of solar wind is
also touched upon.
---------------------------------------------------------
Title: Quasi-Periodic Pulsations in Solar and Stellar Flares:
A Review of Underpinning Physical Mechanisms and Their Predicted
Observational Signatures
Authors: Zimovets, I. V.; McLaughlin, J. A.; Srivastava, A. K.;
Kolotkov, D. Y.; Kuznetsov, A. A.; Kupriyanova, E. G.; Cho, I. -H.;
Inglis, A. R.; Reale, F.; Pascoe, D. J.; Tian, H.; Yuan, D.; Li, D.;
Zhang, Q. M.
2021SSRv..217...66Z Altcode:
The phenomenon of quasi-periodic pulsations (QPPs) in solar and stellar
flares has been known for over 50 years and significant progress has
been made in this research area. It has become clear that QPPs are
not rare—they are found in many flares and, therefore, robust flare
models should reproduce their properties in a natural way. At least
fifteen mechanisms/models have been developed to explain QPPs in solar
flares, which mainly assume the presence of magnetohydrodynamic (MHD)
oscillations in coronal structures (magnetic loops and current sheets)
or quasi-periodic regimes of magnetic reconnection. We review the most
important and interesting results on flare QPPs, with an emphasis on
the results of recent years, and we present the predicted and prominent
observational signatures of each of the fifteen mechanisms. However,
it is not yet possible to draw an unambiguous conclusion as to
the correct underlying QPP mechanism because of the qualitative,
rather than quantitative, nature of most of the models and also due
to insufficient observational information on the physical properties
of the flare region, in particular the spatial structure of the QPP
source. We also review QPPs in stellar flares, where progress is
largely based on solar-stellar analogies, suggesting similarities in
the physical processes in flare regions on the Sun and magnetoactive
stars. The presence of QPPs with similar properties in solar and
stellar flares is, in itself, a strong additional argument in favor
of the likelihood of solar-stellar analogies. Hence, advancing our
understanding of QPPs in solar flares provides an important additional
channel of information about stellar flares. However, further work in
both theory/simulations and in observations is needed.
---------------------------------------------------------
Title: Separating 3<SUP>9</SUP>Ar from 4<SUP>0</SUP>Ar by cryogenic
distillation with Aria for dark-matter searches
Authors: Agnes, P.; Albergo, S.; Albuquerque, I. F. M.; Alexander, T.;
Alici, A.; Alton, A. K.; Amaudruz, P.; Arba, M.; Arpaia, P.; Arcelli,
S.; Ave, M.; Avetissov, I. Ch.; Avetisov, R. I.; Azzolini, O.; Back,
H. O.; Balmforth, Z.; Barbarian, V.; Barrado Olmedo, A.; Barrillon,
P.; Basco, A.; Batignani, G.; Bondar, A.; Bonivento, W. M.; Borisova,
E.; Bottino, B.; Boulay, M. G.; Buccino, G.; Bussino, S.; Busto,
J.; Buzulutskov, A.; Cadeddu, M.; Cadoni, M.; Caminata, A.; Canesi,
E. V.; Canci, N.; Cappello, G.; Caravati, M.; Cárdenas-Montes, M.;
Cargioli, N.; Carlini, M.; Carnesecchi, F.; Castello, P.; Castellani,
A.; Catalanotti, S.; Cataudella, V.; Cavalcante, P.; Cavuoti, S.;
Cebrian, S.; Cela Ruiz, J. M.; Celano, B.; Chashin, S.; Chepurnov,
A.; Cicalò, C.; Cifarelli, L.; Cintas, D.; Coccetti, F.; Cocco, V.;
Colocci, M.; Conde Vilda, E.; Consiglio, L.; Copello, S.; Corning,
J.; Covone, G.; Czudak, P.; D'Aniello, M.; D'Auria, S.; Da Rocha
Rolo, M. D.; Dadoun, O.; Daniel, M.; Davini, S.; De Candia, A.; De
Cecco, S.; De Falco, A.; De Filippis, G.; De Gruttola, D.; De Guido,
G.; De Rosa, G.; Della Valle, M.; Dellacasa, G.; De Pasquale, S.;
Derbin, A. V.; Devoto, A.; Di Noto, L.; Di Eusanio, F.; Dionisi, C.;
Di Stefano, P.; Dolganov, G.; Dongiovanni, D.; Dordei, F.; Downing,
M.; Erjavec, T.; Falciano, S.; Farenzena, S.; Fernandez Diaz, M.;
Filip, C.; Fiorillo, G.; Franceschi, A.; Franco, D.; Frolov, E.;
Funicello, N.; Gabriele, F.; Galbiati, C.; Garbini, M.; Garcia Abia,
P.; Gendotti, A.; Ghiano, C.; Giampaolo, R. A.; Giganti, C.; Giorgi,
M. A.; Giovanetti, G. K.; Gligan, M. L.; Goicoechea Casanueva, V.;
Gola, A.; Goretti, A. M.; Graciani Diaz, R.; Grigoriev, G. Y.; Grobov,
A.; Gromov, M.; Guan, M.; Guerzoni, M.; Guetti, M.; Gulino, M.; Guo,
C.; Hackett, B. R.; Hallin, A.; Haranczyk, M.; Hill, S.; Horikawa,
S.; Hubaut, F.; Hugues, T.; Hungerford, E. V.; Ianni, An.; Ippolito,
V.; James, C. C.; Jillings, C.; Kachru, P.; Kemp, A. A.; Kendziora,
C. L.; Keppel, G.; Khomyakov, A. V.; Kish, A.; Kochanek, I.; Kondo,
K.; Korga, G.; Kubankin, A.; Kugathasan, R.; Kuss, M.; Kuźniak,
M.; La Commara, M.; La Delfa, L.; La Grasta, D.; Lai, M.; Lami, N.;
Langrock, S.; Leyton, M.; Li, X.; Lidey, L.; Lippi, F.; Lissia, M.;
Longo, G.; Maccioni, N.; Machulin, I. N.; Mapelli, L.; Marasciulli, A.;
Margotti, A.; Mari, S. M.; Maricic, J.; Marinelli, M.; Martínez, M.;
Martinez Rojas, A. D.; Martini, A.; Mascia, M.; Masetto, M.; Masoni,
A.; Mazzi, A.; McDonald, A. B.; Mclaughlin, J.; Messina, A.; Meyers,
P. D.; Miletic, T.; Milincic, R.; Miola, R.; Moggi, A.; Moharana,
A.; Moioli, S.; Monroe, J.; Morisi, S.; Morrocchi, M.; Mozhevitina,
E. N.; Mróz, T.; Muratova, V. N.; Murenu, A.; Muscas, C.; Musenich,
L.; Musico, P.; Nania, R.; Napolitano, T.; Navrer Agasson, A.; Nessi,
M.; Nikulin, I.; Nowak, J.; Oleinik, A.; Oleynikov, V.; Pagani, L.;
Pallavicini, M.; Palmas, S.; Pandola, L.; Pantic, E.; Paoloni, E.;
Paternoster, G.; Pegoraro, P. A.; Pellegrini, L. A.; Pellegrino,
C.; Pelczar, K.; Perotti, F.; Pesudo, V.; Picciau, E.; Pietropaolo,
F.; Pinna, T.; Pocar, A.; Podda, P.; Poehlmann, D. M.; Pordes, S.;
Poudel, S. S.; Pralavorio, P.; Price, D.; Raffaelli, F.; Ragusa, F.;
Ramirez, A.; Razeti, M.; Razeto, A.; Renshaw, A. L.; Rescia, S.;
Rescigno, M.; Resnati, F.; Retiere, F.; Rignanese, L. P.; Ripoli,
C.; Rivetti, A.; Rode, J.; Romero, L.; Rossi, M.; Rubbia, A.; Rucaj,
M.; Sabiu, G. M.; Salatino, P.; Samoylov, O.; Sánchez García, E.;
Sandford, E.; Sanfilippo, S.; Sangiorgio, V. A.; Santacroce, V.;
Santone, D.; Santorelli, R.; Santucci, A.; Savarese, C.; Scapparone,
E.; Schlitzer, B.; Scioli, G.; Semenov, D. A.; Shaw, B.; Shchagin,
A.; Sheshukov, A.; Simeone, M.; Skensved, P.; Skorokhvatov, M. D.;
Smirnov, O.; Smith, B.; Sokolov, A.; Stefanizzi, R.; Steri, A.;
Stracka, S.; Strickland, V.; Stringer, M.; Sulis, S.; Suvorov, Y.;
Szelc, A. M.; Szucs-Balazs, J. Z.; Tartaglia, R.; Testera, G.; Thorpe,
T. N.; Tonazzo, A.; Torres-Lara, S.; Tosti, S.; Tricomi, A.; Tuveri,
M.; Unzhakov, E. V.; Usai, G.; Vallivilayil John, T.; Vescovi, S.;
Viant, T.; Viel, S.; Vishneva, A.; Vogelaar, R. B.; Wada, M.; Wang,
H.; Wang, Y.; Westerdale, S.; Wheadon, R. J.; Williams, L.; M. Wojcik,
Ma.; Wojcik, Ma.; Xiao, X.; Yang, C.; Zani, A.; Zenobio, F.; Zichichi,
A.; Zuzel, G.; Zykova, M. P.; DarkSide-20k Collaboration
2021EPJC...81..359A Altcode: 2021arXiv210108686D
Aria is a plant hosting a 350 m cryogenic isotopic distillation
column, the tallest ever built, which is being installed in a mine
shaft at Carbosulcis S.p.A., Nuraxi-Figus (SU), Italy. Aria is one
of the pillars of the argon dark-matter search experimental program,
lead by the Global Argon Dark Matter Collaboration. It was designed
to reduce the isotopic abundance of 3<SUP>9</SUP>Ar in argon extracted
from underground sources, called Underground Argon (UAr), which is used
for dark-matter searches. Indeed, 3<SUP>9</SUP>Ar is a β -emitter
of cosmogenic origin, whose activity poses background and pile-up
concerns in the detectors. In this paper, we discuss the requirements,
design, construction, tests, and projected performance of the plant
for the isotopic cryogenic distillation of argon. We also present the
successful results of the isotopic cryogenic distillation of nitrogen
with a prototype plant.
---------------------------------------------------------
Title: Sensitivity of future liquid argon dark matter search
experiments to core-collapse supernova neutrinos
Authors: DarkSide-20k Collaboration; Agnes, P.; Albergo, S.;
Albuquerque, I. F. M.; Alexander, T.; Alici, A.; Alton, A. K.;
Amaudruz, P.; Arcelli, S.; Ave, M.; Avetissov, I. Ch.; Avetisov, R. I.;
Azzolini, O.; Back, H. O.; Balmforth, Z.; Barbarian, V.; Barrado
Olmedo, A.; Barrillon, P.; Basco, A.; Batignani, G.; Bondar, A.;
Bonivento, W. M.; Borisova, E.; Bottino, B.; Boulay, M. G.; Buccino,
G.; Bussino, S.; Busto, J.; Buzulutskov, A.; Cadeddu, M.; Cadoni, M.;
Caminata, A.; Canci, N.; Cappello, G.; Caravati, M.; Cárdenas-Montes,
M.; Carlini, M.; Carnesecchi, F.; Castello, P.; Catalanotti, S.;
Cataudella, V.; Cavalcante, P.; Cavuoti, S.; Cebrian, S.; Cela
Ruiz, J. M.; Celano, B.; Chashin, S.; Chepurnov, A.; Chyhyrynets,
E.; Cicalò, C.; Cifarelli, L.; Cintas, D.; Coccetti, F.; Cocco, V.;
Colocci, M.; Conde Vilda, E.; Consiglio, L.; Copello, S.; Corning, J.;
Covone, G.; Czudak, P.; D'Auria, S.; Da Rocha Rolo, M. D.; Dadoun,
O.; Daniel, M.; Davini, S.; De Candia, A.; De Cecco, S.; De Falco,
A.; De Filippis, G.; De Gruttola, D.; De Guido, G.; De Rosa, G.; Della
Valle, M.; Dellacasa, G.; De Pasquale, S.; Derbin, A. V.; Devoto, A.;
Di Noto, L.; Dionisi, C.; Di Stefano, P.; Dolganov, G.; Dordei, F.;
Doria, L.; Downing, M.; Erjavec, T.; Fernandez Diaz, M.; Fiorillo,
G.; Franceschi, A.; Franco, D.; Frolov, E.; Funicello, N.; Gabriele,
F.; Galbiati, C.; Garbini, M.; Garcia Abia, P.; Gendotti, A.; Ghiano,
C.; Giampaolo, R. A.; Giganti, C.; Giorgi, M. A.; Giovanetti, G. K.;
Goicoechea Casanueva, V.; Gola, A.; Graciani Diaz, R.; Grigoriev,
G. Y.; Grobov, A.; Gromov, M.; Guan, M.; Guerzoni, M.; Gulino, M.; Guo,
C.; Hackett, B. R.; Hallin, A.; Haranczyk, M.; Hill, S.; Horikawa,
S.; Hubaut, F.; Hugues, T.; Hungerford, E. V.; Ianni, An.; Ippolito,
V.; James, C. C.; Jillings, C.; Kachru, P.; Kemp, A. A.; Kendziora,
C. L.; Keppel, G.; Khomyakov, A. V.; Kim, S.; Kish, A.; Kochanek,
I.; Kondo, K.; Korga, G.; Kubankin, A.; Kugathasan, R.; Kuss, M.;
Kuźniak, M.; La Commara, M.; Lai, M.; Langrock, S.; Leyton, M.; Li,
X.; Lidey, L.; Lissia, M.; Longo, G.; Machulin, I. N.; Mapelli, L.;
Marasciulli, A.; Margotti, A.; Mari, S. M.; Maricic, J.; Martínez,
M.; Martinez Rojas, A. D.; Martoff, C. J.; Masoni, A.; Mazzi, A.;
McDonald, A. B.; Mclaughlin, J.; Messina, A.; Meyers, P. D.; Miletic,
T.; Milincic, R.; Moggi, A.; Moharana, A.; Moioli, S.; Monroe, J.;
Morisi, S.; Morrocchi, M.; Mozhevitina, E. N.; Mróz, T.; Muratova,
V. N.; Muscas, C.; Musenich, L.; Musico, P.; Nania, R.; Napolitano,
T.; Navrer Agasson, A.; Nessi, M.; Nikulin, I.; Nowak, J.; Oleinik,
A.; Oleynikov, V.; Pagani, L.; Pallavicini, M.; Pandola, L.; Pantic,
E.; Paoloni, E.; Paternoster, G.; Pegoraro, P. A.; Pelczar, K.;
Pellegrini, L. A.; Pellegrino, C.; Perotti, F.; Pesudo, V.; Picciau,
E.; Pietropaolo, F.; Pira, C.; Pocar, A.; Poehlmann, D. M.; Pordes,
S.; Poudel, S. S.; Pralavorio, P.; Price, D.; Raffaelli, F.; Ragusa,
F.; Ramirez, A.; Razeti, M.; Razeto, A.; Renshaw, A. L.; Rescia, S.;
Rescigno, M.; Resnati, F.; Retiere, F.; Rignanese, L. P.; Ripoli, C.;
Rivetti, A.; Rode, J.; Romero, L.; Rossi, M.; Rubbia, A.; Salatino,
P.; Samoylov, O.; Sánchez García, E.; Sandford, E.; Sanfilippo, S.;
Santone, D.; Santorelli, R.; Savarese, C.; Scapparone, E.; Schlitzer,
B.; Scioli, G.; Semenov, D. A.; Shaw, B.; Shchagin, A.; Sheshukov, A.;
Simeone, M.; Skensved, P.; Skorokhvatov, M. D.; Smirnov, O.; Smith,
B.; Sokolov, A.; Steri, A.; Stracka, S.; Strickland, V.; Stringer,
M.; Sulis, S.; Suvorov, Y.; Szelc, A. M.; Tartaglia, R.; Testera, G.;
Thorpe, T. N.; Tonazzo, A.; Torres-Lara, S.; Tricomi, A.; Unzhakov,
E. V.; Usai, G.; Vallivilayil John, T.; Viant, T.; Viel, S.; Vishneva,
A.; Vogelaar, R. B.; Wada, M.; Wang, H.; Wang, Y.; Westerdale, S.;
Wheadon, R. J.; Williams, L.; Wojcik, Ma. M.; Wojcik, Ma.; Xiao, X.;
Yang, C.; Ye, Z.; Zani, A.; Zichichi, A.; Zuzel, G.; Zykova, M. P.
2021JCAP...03..043D Altcode: 2021JCAP...03..043T; 2020arXiv201107819A
Future liquid-argon DarkSide-20k and Argo detectors, designed for direct
dark matter search, will be sensitive also to core-collapse supernova
neutrinos, via coherent elastic neutrino-nucleus scattering. This
interaction channel is flavor-insensitive with a high-cross section,
enabling for a high-statistics neutrino detection with target masses
of ∼50 t and ∼360 t for DarkSide-20k and Argo respectively. Thanks
to the low-energy threshold of ∼0.5 keV<SUB>nr</SUB> achievable
by exploiting the ionization channel, DarkSide-20k and Argo have the
potential to discover supernova bursts throughout our galaxy and up to
the Small Magellanic Cloud, respectively, assuming a 11-M<SUB>⊙</SUB>
progenitor star. We report also on the sensitivity to the neutronization
burst, whose electron neutrino flux is suppressed by oscillations
when detected via charged current and elastic scattering. Finally,
the accuracies in the reconstruction of the average and total neutrino
energy in the different phases of the supernova burst, as well as its
time profile, are also discussed, taking into account the expected
background and the detector response.
---------------------------------------------------------
Title: Simulations of events for the LUX-ZEPLIN (LZ) dark matter
experiment
Authors: Akerib, D. S.; Akerlof, C. W.; Alqahtani, A.; Alsum, S. K.;
Anderson, T. J.; Angelides, N.; Araújo, H. M.; Armstrong, J. E.;
Arthurs, M.; Bai, X.; Balajthy, J.; Balashov, S.; Bang, J.; Bauer, D.;
Baxter, A.; Bensinger, J.; Bernard, E. P.; Bernstein, A.; Bhatti, A.;
Biekert, A.; Biesiadzinski, T. P.; Birch, H. J.; Boast, K. E.; Boxer,
B.; Brás, P.; Buckley, J. H.; Bugaev, V. V.; Burdin, S.; Busenitz,
J. K.; Cabrita, R.; Carels, C.; Carlsmith, D. L.; Carmona-Benitez,
M. C.; Cascella, M.; Chan, C.; Chott, N. I.; Cole, A.; Cottle,
A.; Cutter, J. E.; Dahl, C. E.; Viveiros, L. de; Dobson, J. E. Y.;
Druszkiewicz, E.; Edberg, T. K.; Eriksen, S. R.; Fan, A.; Fayer, S.;
Fiorucci, S.; Flaecher, H.; Fraser, E. D.; Fruth, T.; Gaitskell,
R. J.; Genovesi, J.; Ghag, C.; Gibson, E.; Gilchriese, M. G. D.;
Gokhale, S.; van der Grinten, M. G. D.; Hall, C. R.; Harrison, A.;
Haselschwardt, S. J.; Hertel, S. A.; Hor, J. Y. -K.; Horn, M.; Huang,
D. Q.; Ignarra, C. M.; Jahangir, O.; Ji, W.; Johnson, J.; Kaboth,
A. C.; Kamaha, A. C.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Khazov,
A.; Khurana, I.; Kocher, C. D.; Korley, L.; Korolkova, E. V.; Kras,
J.; Kraus, H.; Kravitz, S.; Kreczko, L.; Krikler, B.; Kudryavtsev,
V. A.; Leason, E. A.; Lee, J.; Leonard, D. S.; Lesko, K. T.; Levy,
C.; Li, J.; Liao, J.; Liao, F. -T.; Lin, J.; Lindote, A.; Linehan,
R.; Lippincott, W. H.; Liu, R.; Liu, X.; Loniewski, C.; Lopes, M. I.;
López Paredes, B.; Lorenzon, W.; Luitz, S.; Lyle, J. M.; Majewski,
P. A.; Manalaysay, A.; Manenti, L.; Mannino, R. L.; Marangou, N.;
Marzioni, M. F.; McKinsey, D. N.; McLaughlin, J.; Meng, Y.; Miller,
E. H.; Mizrachi, E.; Monte, A.; Monzani, M. E.; Morad, J. A.; Morrison,
E.; Mount, B. J.; Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.;
Nehrkorn, C.; Nelson, H. N.; Neves, F.; Nikoleyczik, J. A.; Nilima, A.;
Olcina, I.; Oliver-Mallory, K. C.; Pal, S.; Palladino, K. J.; Palmer,
J.; Parveen, N.; Pease, E. K.; Penning, B.; Pereira, G.; Piepke, A.;
Pushkin, K.; Reichenbacher, J.; Rhyne, C. A.; Richards, A.; Riffard,
Q.; Rischbieter, G. R. C.; Rosero, R.; Rossiter, P.; Rutherford,
G.; Santone, D.; Sazzad, A. B. M. R.; Schnee, R. W.; Schubnell, M.;
Scovell, P. R.; Seymour, D.; Shaw, S.; Shutt, T. A.; Silk, J. J.;
Silva, C.; Smith, R.; Solmaz, M.; Solovov, V. N.; Sorensen, P.;
Stancu, I.; Stevens, A.; Stifter, K.; Sumner, T. J.; Swanson, N.;
Szydagis, M.; Tan, M.; Taylor, W. C.; Taylor, R.; Temples, D. J.;
Terman, P. A.; Tiedt, D. R.; Timalsina, M.; Tomás, A.; Tripathi,
M.; Tronstad, D. R.; Turner, W.; Tvrznikova, L.; Utku, U.; Vacheret,
A.; Vaitkus, A.; Wang, J. J.; Wang, W.; Watson, J. R.; Webb, R. C.;
White, R. G.; Whitis, T. J.; Wolfs, F. L. H.; Woodward, D.; Xiang,
X.; Xu, J.; Yeh, M.; Zarzhitsky, P.
2021APh...12502480A Altcode:
The LUX-ZEPLIN dark matter search aims to achieve a sensitivity
to the WIMP-nucleon spin-independent cross-section down to (1-2)
×10<SUP>-12</SUP> pb at a WIMP mass of 40 GeV/c<SUP>2</SUP>. This
paper describes the simulations framework that, along with radioactivity
measurements, was used to support this projection, and also to provide
mock data for validating reconstruction and analysis software. Of
particular note are the event generators, which allow us to model
the background radiation, and the detector response physics used in
the production of raw signals, which can be converted into digitized
waveforms similar to data from the operational detector. Inclusion of
the detector response allows us to process simulated data using the
same analysis routines as developed to process the experimental data.
---------------------------------------------------------
Title: Enhancing the sensitivity of the LUX-ZEPLIN (LZ) dark matter
experiment to low energy signals
Authors: Akerib, D. S.; Al Musalhi, A. K.; Alsum, S. K.; Amarasinghe,
C. S.; Ames, A.; Anderson, T. J.; Angelides, N.; Araújo, H. M.;
Armstrong, J. E.; Arthurs, M.; Bai, X.; Balajthy, J.; Balashov,
S.; Bang, J.; Bargemann, J. W.; Bauer, D.; Baxter, A.; Beltrame, P.;
Bernard, E. P.; Bernstein, A.; Bhatti, A.; Biekert, A.; Biesiadzinski,
T. P.; Birch, H. J.; Blockinger, G. M.; Boxer, B.; Brew, C. A. J.;
Brás, P.; Burdin, S.; Busenitz, J. K.; Buuck, M.; Cabrita, R.;
Carmona-Benitez, M. C.; Cascella, M.; Chan, C.; Chott, N. I.; Cole,
A.; Converse, M. V.; Cottle, A.; Cox, G.; Cutter, J. E.; Dahl,
C. E.; de Viveiros, L.; Dobson, J. E. Y.; Druszkiewicz, E.; Eriksen,
S. R.; Fan, A.; Fayer, S.; Fearon, N. M.; Fiorucci, S.; Flaecher,
H.; Fraser, E. D.; Fruth, T.; Gaitskell, R. J.; Genovesi, J.; Ghag,
C.; Gibson, E.; Gokhale, S.; van der Grinten, M. G. D.; Gwilliam,
C. B.; Hall, C. R.; Haselschwardt, S. J.; Hertel, S. A.; Horn,
M.; Huang, D. Q.; Ignarra, C. M.; Jahangir, O.; James, R. S.; Ji,
W.; Johnson, J.; Kaboth, A. C.; Kamaha, A. C.; Kamdin, K.; Kazkaz,
K.; Khaitan, D.; Khazov, A.; Khurana, I.; Kodroff, D.; Korley, L.;
Korolkova, E. V.; Kraus, H.; Kravitz, S.; Kreczko, L.; Krikler, B.;
Kudryavtsev, V. A.; Leason, E. A.; Lesko, K. T.; Levy, C.; Li, J.;
Liao, J.; Lin, J.; Lindote, A.; Linehan, R.; Lippincott, W. H.; Liu,
X.; Lopes, M. I.; Lopez Asamar, E.; López Paredes, B.; Lorenzon, W.;
Luitz, S.; Majewski, P. A.; Manalaysay, A.; Manenti, L.; Mannino,
R. L.; Marangou, N.; McCarthy, M. E.; McKinsey, D. N.; McLaughlin,
J.; Miller, E. H.; Mizrachi, E.; Monte, A.; Monzani, M. E.; Morad,
J. A.; Morales Mendoza, J. D.; Morrison, E.; Mount, B. J.; Murphy,
A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.; Nelson, H. N.; Neves,
F.; Nikoleyczik, J. A.; Olcina, I.; Oliver-Mallory, K. C.; Pal, S.;
Palladino, K. J.; Palmer, J.; Parveen, N.; Pease, E. K.; Penning, B.;
Pereira, G.; Piepke, A.; Qie, Y.; Reichenbacher, J.; Rhyne, C. A.;
Richards, A.; Riffard, Q.; Rischbieter, G. R. C.; Rosero, R.; Rossiter,
P.; Santone, D.; Sazzad, A. B. M. R.; Schnee, R. W.; Scovell, P. R.;
Shaw, S.; Shutt, T. A.; Silk, J. J.; Silva, C.; Smith, R.; Solmaz, M.;
Solovov, V. N.; Sorensen, P.; Stancu, I.; Stevens, A.; Stifter, K.;
Suerfu, B.; Sumner, T. J.; Swanson, N.; Szydagis, M.; Taylor, W. C.;
Taylor, R.; Temples, D. J.; Terman, P. A.; Tiedt, D. R.; Timalsina,
M.; To, W. H.; Tripathi, M.; Tronstad, D. R.; Turner, W.; Utku, U.;
Vaitkus, A.; Wang, B.; Wang, J. J.; Wang, W.; Watson, J. R.; Webb,
R. C.; White, R. G.; Whitis, T. J.; Williams, M.; Wolfs, F. L. H.;
Woodward, D.; Wright, C. J.; Xiang, X.; Xu, J.; Yeh, M.; Zarzhitsky, P.
2021arXiv210108753A Altcode:
Two-phase xenon detectors, such as that at the core of the forthcoming
LZ dark matter experiment, use photomultiplier tubes to sense the
primary (S1) and secondary (S2) scintillation signals resulting
from particle interactions in their liquid xenon target. This paper
describes a simulation study exploring two techniques to lower the
energy threshold of LZ to gain sensitivity to low-mass dark matter
and astrophysical neutrinos, which will be applicable to other liquid
xenon detectors. The energy threshold is determined by the number of
detected S1 photons; typically, these must be recorded in three or
more photomultiplier channels to avoid dark count coincidences that
mimic real signals. To lower this threshold: a) we take advantage of
the double photoelectron emission effect, whereby a single vacuum
ultraviolet photon has a $\sim20\%$ probability of ejecting two
photoelectrons from a photomultiplier tube photocathode; and b) we drop
the requirement of an S1 signal altogether, and use only the ionization
signal, which can be detected more efficiently. For both techniques
we develop signal and background models for the nominal exposure, and
explore accompanying systematic effects, including the dependence on the
free electron lifetime in the liquid xenon. When incorporating double
photoelectron signals, we predict a factor of $\sim 4$ sensitivity
improvement to the dark matter-nucleon scattering cross-section at
$2.5$ GeV/c$^2$, and a factor of $\sim1.6$ increase in the solar
$^8$B neutrino detection rate. Dropping the S1 requirement may allow
sensitivity gains of two orders of magnitude in both cases. Finally,
we apply these techniques to even lower masses by taking into account
the atomic Migdal effect; this could lower the dark matter particle
mass threshold to $80$ MeV/c$^2$.
---------------------------------------------------------
Title: Using Transverse Waves to Probe the Plasma Conditions at the
Base of the Solar Wind
Authors: Weberg, Micah J.; Morton, Richard J.; McLaughlin, James A.
2020ApJ...894...79W Altcode:
It has long been suggested that magnetohydrodynamic (MHD) waves may
supply a significant proportion of the energy required to heat the
corona and accelerate the solar wind. Depending on the properties of
the local plasma, MHD wave modes may exhibit themselves as a variety of
incompressible, transverse waves. The local magnetic field and particle
density influence the properties of these waves (e.g., amplitude),
thus direct measurements of transverse waves provide a mechanism to
indirectly probe the local plasma conditions. We present the first
statistical approach to magnetoseismology of a localized region of the
solar corona, analyzing transverse waves above the south polar coronal
hole on 2011 May 23. Automated methods are utilized to examine 4 hr of
EUV imaging data to study how the waves evolve as a function of height
(I.e., altitude) through the low corona. Between heights of 15 and 35
Mm, we find that the measured wave periods are approximately constant,
and that observed displacement and velocity amplitudes increase at
rates that are consistent with undamped waves. This enables us to
derive a relative density profile for the coronal hole environment
in question, without the use of spectroscopic data. Furthermore,
our results indicate that between 5 and 15 Mm above the limb, the
relative density is larger than that expected from 1D hydrostatic
models, and signals a more extended transition region with a gradual
change in density. This has implications for self-consistent models
of wave propagation from the photosphere to the corona and beyond.
---------------------------------------------------------
Title: Measurement of the gamma ray background in the Davis cavern
at the Sanford Underground Research Facility
Authors: Akerib, D. S.; Akerlof, C. W.; Alsum, S. K.; Angelides, N.;
Araújo, H. M.; Armstrong, J. E.; Arthurs, M.; Bai, X.; Balajthy, J.;
Balashov, S.; Baxter, A.; Bernard, E. P.; Biekert, A.; Biesiadzinski,
T. P.; Boast, K. E.; Boxer, B.; Brás, P.; Buckley, J. H.; Bugaev,
V. V.; Burdin, S.; Busenitz, J. K.; Carels, C.; Carlsmith, D. L.;
Carmona-Benitez, M. C.; Cascella, M.; Chan, C.; Cole, A.; Cottle,
A.; Cutter, J. E.; Dahl, C. E.; de Viveiros, L.; Dobson, J. E. Y.;
Druszkiewicz, E.; Edberg, T. K.; Fan, A.; Fiorucci, S.; Flaecher,
H.; Fruth, T.; Gaitskell, R. J.; Genovesi, J.; Ghag, C.; Gilchriese,
M. G. D.; Gokhale, S.; van der Grinten, M. G. D.; Hall, C. R.;
Hans, S.; Harrison, J.; Haselschwardt, S. J.; Hertel, S. A.; Hor,
J. Y. -K.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Jahangir, O.; Ji,
W.; Johnson, J.; Kaboth, A. C.; Kamdin, K.; Khaitan, D.; Khazov, A.;
Kim, W. T.; Kocher, C. D.; Korley, L.; Korolkova, E. V.; Kras, J.;
Kraus, H.; Kravitz, S. W.; Kreczko, L.; Krikler, B.; Kudryavtsev,
V. A.; Leason, E. A.; Lee, J.; Leonard, D. S.; Lesko, K. T.; Levy,
C.; Li, J.; Liao, J.; Liao, F. -T.; Lin, J.; Lindote, A.; Linehan,
R.; Lippincott, W. H.; Liu, R.; Liu, X.; Loniewski, C.; Lopes, M. I.;
López Paredes, B.; Lorenzon, W.; Luitz, S.; Lyle, J. M.; Majewski,
P. A.; Manalaysay, A.; Manenti, L.; Mannino, R. L.; Marangou, N.;
Marzioni, M. F.; McKinsey, D. N.; McLaughlin, J.; Meng, Y.; Miller,
E. H.; Monzani, M. E.; Morad, J. A.; Morrison, E.; Mount, B. J.;
Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.; Nehrkorn,
C.; Nelson, H. N.; Neves, F.; Nikoleyczik, J.; Nilima, A.; Olcina,
I.; Oliver-Mallory, K. C.; Pal, S.; Palladino, K. J.; Pease, E. K.;
Penning, B. P.; Pereira, G.; Piepke, A.; Pushkin, K.; Reichenbacher,
J.; Rhyne, C. A.; Riffard, Q.; Rischbieter, G. R. C.; Rodrigues,
J. P.; Rosero, R.; Rossiter, P.; Rutherford, G.; Sazzad, A. B. M. R.;
Schnee, R. W.; Schubnell, M.; Scovell, P. R.; Seymour, D.; Shaw, S.;
Shutt, T. A.; Silk, J. J.; Silva, C.; Solmaz, M.; Solovov, V. N.;
Sorensen, P.; Stancu, I.; Stevens, A.; Stiegler, T. M.; Stifter, K.;
Szydagis, M.; Taylor, W. C.; Taylor, R.; Temples, D.; Terman, P. A.;
Tiedt, D. R.; Timalsina, M.; Tomás, A.; Tripathi, M.; Tvrznikova,
L.; Utku, U.; Uvarov, S.; Vacheret, A.; Wang, J. J.; Watson, J. R.;
Webb, R. C.; White, R. G.; Whitis, T. J.; Wolfs, F. L. H.; Woodward,
D.; Yin, J.; Lux-Zeplin (Lz) Collaboration
2020APh...11602391A Altcode: 2019arXiv190402112A
Deep underground environments are ideal for low background searches due
to the attenuation of cosmic rays by passage through the earth. However,
they are affected by backgrounds from γ-rays emitted by <SUP>40</SUP>K
and the <SUP>238</SUP>U and <SUP>232</SUP>Th decay chains in the
surrounding rock. The LUX-ZEPLIN (LZ) experiment will search for dark
matter particle interactions with a liquid xenon TPC located within the
Davis campus at the Sanford Underground Research Facility, Lead, South
Dakota, at the 4850-foot level. In order to characterise the cavern
background, in-situ γ-ray measurements were taken with a sodium iodide
detector in various locations and with lead shielding. The integral
count rates (0-3300 keV) varied from 596 Hz to 1355 Hz for unshielded
measurements, corresponding to a total flux from the cavern walls of
1.9 ± 0.4 γ cm-<SUP>2</SUP>s-<SUP>1</SUP>. The resulting activity
in the walls of the cavern can be characterised as 220 ± 60 Bq/kg of
<SUP>40</SUP>K, 29 ± 15 Bq/kg of <SUP>238</SUP>U, and 13 ± 3 Bq/kg
of <SUP>232</SUP>Th.
---------------------------------------------------------
Title: Exploring Flaring Behaviour on Low Mass Stars, Solar-type
Stars and the Sun
Authors: Doyle, L.; Ramsay, G.; Doyle, J. G.; Wyper, P. F.; Scullion,
E.; Wu, K.; McLaughlin, J. A.
2020IAUS..354..384D Altcode:
We report on our project to study the activity in both the Sun and low
mass stars. Utilising high cadence, Hα observations of a filament
eruption made using the CRISP spectropolarimeter mounted on the
Swedish Solar Telescope has allowed us to determine 3D velocity maps
of the event. To gain insight into the physical mechanism which drives
the event we have qualitatively compared our observation to a 3D MHD
reconnection model. Solar-type and low mass stars can be highly active
producing flares with energies exceeding erg. Using K2 and TESS data
we find no correlation between the number of flares and the rotation
phase which is surprising. Our solar flare model can be used to aid
our understanding of the origin of flares in other stars. By scaling
up our solar model to replicate observed stellar flare energies,
we investigate the conditions needed for such high energy flares.
---------------------------------------------------------
Title: Pan-STARRS Search for Kilonovae: discovery of PS19hgw, an
intrinsically faint transient in KUG 0152+311 (144 Mpc)
Authors: S; McLaughlin; Smartt, S. J.; Smith, K. W.; Chambers, K. C.;
Huber, M.; Srivastav, S.; McBrien, O.; Young, D. R.; Gillanders, J.;
O'Neill, D.; Clark, P.; Sim, S.; Boer, T. D.; Bulger, J.; Fairlamb,
J.; Lin, C. C.; Lowe, T.; Magnier, E.; Schultz, A.; Wainscoat, R. J.;
Willman, M.; Chen, T. W.; Wright, D. E.; Stubbs, C.; Rest, A.
2019TNSAN.154....1S Altcode:
We are carrying out the "Pan-STARRS Search for Kilonovae" which is a
focused search for intrinsically faint transients, or rapidly evolving
transients in galaxies which are closer than 200 Mpc in the ongoing
Pan-STARRS Near Earth Object surveys (see Smartt et al. AstroNote
2019-48 for details). Here we report the discovery of an intrinsically
faint transient PS19hgw (AT2019wxt) in the host galaxy KUG 0152+311, at
a redshift of z = 0.036, or d = 144 Mpc (from NED). It has an absolute
magnitude at discovery of M_i = -16.6. We note that this is in the 80%
contour of the skymap of the possible BNS gravitational wave source
S191213g (the LALInference.fits.gz, The LIGO Scientific Collaboration
and the Virgo Collaboration, GCN 26402), was discovered after the merger
time, and is at a distance consistent with the parameter estimation
of LVC for this event.
---------------------------------------------------------
Title: Observations and 3D Magnetohydrodynamic Modeling of a Confined
Helical Jet Launched by a Filament Eruption
Authors: Doyle, Lauren; Wyper, Peter F.; Scullion, Eamon; McLaughlin,
James A.; Ramsay, Gavin; Doyle, J. Gerard
2019ApJ...887..246D Altcode: 2019arXiv191202133D
We present a detailed analysis of a confined filament eruption
and jet associated with a C1.5 class solar flare. Multi-wavelength
observations from the Global Oscillations Network Group and Solar
Dynamics Observatory reveal the filament forming over several days
following the emergence and then partial cancellation of a minority
polarity spot within a decaying bipolar active region. The emergence
is also associated with the formation of a 3D null point separatrix
that surrounds the minority polarity. The filament eruption occurs
concurrently with brightenings adjacent to and below the filament,
suggestive of breakout and flare reconnection, respectively. The
erupting filament material becomes partially transferred into a
strong outflow jet (∼60 km s<SUP>-1</SUP>) along coronal loops,
becoming guided back toward the surface. Utilizing high-resolution
Hα observations from the Swedish Solar Telescope/CRisp Imaging
SpectroPolarimeter, we construct velocity maps of the outflows,
demonstrating their highly structured but broadly helical nature. We
contrast the observations with a 3D magnetohydrodynamic simulation
of a breakout jet in a closed-field background and find close
qualitative agreement. We conclude that the suggested model provides
an intuitive mechanism for transferring twist/helicity in confined
filament eruptions, thus validating the applicability of the breakout
model not only to jets and coronal mass ejections but also to confined
eruptions and flares.
---------------------------------------------------------
Title: A Blueprint of State-of-the-art Techniques for Detecting
Quasi-periodic Pulsations in Solar and Stellar Flares
Authors: Broomhall, Anne-Marie; Davenport, James R. A.; Hayes, Laura
A.; Inglis, Andrew R.; Kolotkov, Dmitrii Y.; McLaughlin, James A.;
Mehta, Tishtrya; Nakariakov, Valery M.; Notsu, Yuta; Pascoe, David J.;
Pugh, Chloe E.; Van Doorsselaere, Tom
2019ApJS..244...44B Altcode: 2019arXiv191008458B
Quasi-periodic pulsations (QPPs) appear to be a common feature observed
in the light curves of both solar and stellar flares. However, their
quasi-periodic nature, along with the fact that they can be small
in amplitude and short-lived, makes QPPs difficult to unequivocally
detect. In this paper, we test the strengths and limitations of
state-of-the-art methods for detecting QPPs using a series of
hare-and-hounds exercises. The hare simulated a set of flares,
both with and without QPPs of a variety of forms, while the hounds
attempted to detect QPPs in blind tests. We use the results of these
exercises to create a blueprint for anyone who wishes to detect QPPs
in real solar and stellar data. We present eight clear recommendations
to be kept in mind for future QPP detections, with the plethora of
solar and stellar flare data from new and future satellites. These
recommendations address the key pitfalls in QPP detection, including
detrending, trimming data, accounting for colored noise, detecting
stationary-period QPPs, detecting QPPs with nonstationary periods,
and ensuring that detections are robust and false detections are
minimized. We find that QPPs can be detected reliably and robustly
by a variety of methods, which are clearly identified and described,
if the appropriate care and due diligence are taken.
---------------------------------------------------------
Title: The LUX-ZEPLIN (LZ) Experiment
Authors: The LZ Collaboration; Akerib, D. S.; Akerlof, C. W.; Akimov,
D. Yu.; Alquahtani, A.; Alsum, S. K.; Anderson, T. J.; Angelides, N.;
Araújo, H. M.; Arbuckle, A.; Armstrong, J. E.; Arthurs, M.; Auyeung,
H.; Bai, X.; Bailey, A. J.; Balajthy, J.; Balashov, S.; Bang, J.;
Barry, M. J.; Barthel, J.; Bauer, D.; Bauer, P.; Baxter, A.; Belle, J.;
Beltrame, P.; Bensinger, J.; Benson, T.; Bernard, E. P.; Bernstein,
A.; Bhatti, A.; Biekert, A.; Biesiadzinski, T. P.; Birrittella, B.;
Boast, K. E.; Bolozdynya, A. I.; Boulton, E. M.; Boxer, B.; Bramante,
R.; Branson, S.; Brás, P.; Breidenbach, M.; Buckley, J. H.; Bugaev,
V. V.; Bunker, R.; Burdin, S.; Busenitz, J. K.; Campbell, J. S.;
Carels, C.; Carlsmith, D. L.; Carlson, B.; Carmona-Benitez, M. C.;
Cascella, M.; Chan, C.; Cherwinka, J. J.; Chiller, A. A.; Chiller,
C.; Chott, N. I.; Cole, A.; Coleman, J.; Colling, D.; Conley, R. A.;
Cottle, A.; Coughlen, R.; Craddock, W. W.; Curran, D.; Currie, A.;
Cutter, J. E.; da Cunha, J. P.; Dahl, C. E.; Dardin, S.; Dasu, S.;
Davis, J.; Davison, T. J. R.; de Viveiros, L.; Decheine, N.; Dobi,
A.; Dobson, J. E. Y.; Druszkiewicz, E.; Dushkin, A.; Edberg, T. K.;
Edwards, W. R.; Edwards, B. N.; Edwards, J.; Elnimr, M. M.; Emmet,
W. T.; Eriksen, S. R.; Faham, C. H.; Fan, A.; Fayer, S.; Fiorucci,
S.; Flaecher, H.; Fogarty Florang, I. M.; Ford, P.; Francis, V. B.;
Froborg, F.; Fruth, T.; Gaitskell, R. J.; Gantos, N. J.; Garcia, D.;
Geffre, A.; Gehman, V. M.; Gelfand, R.; Genovesi, J.; Gerhard, R. M.;
Ghag, C.; Gibson, E.; Gilchriese, M. G. D.; Gokhale, S.; Gomber,
B.; Gonda, T. G.; Greenall, A.; Greenwood, S.; Gregerson, G.; van
der Grinten, M. G. D.; Gwilliam, C. B.; Hall, C. R.; Hamilton, D.;
Hans, S.; Hanzel, K.; Harrington, T.; Harrison, A.; Hasselkus, C.;
Haselschwardt, S. J.; Hemer, D.; Hertel, S. A.; Heise, J.; Hillbrand,
S.; Hitchcock, O.; Hjemfelt, C.; Hoff, M. D.; Holbrook, B.; Holtom,
E.; Y-K. Hor, J.; Horn, M.; Huang, D. Q.; Hurteau, T. W.; Ignarra,
C. M.; Irving, M. N.; Jacobsen, R. G.; Jahangir, O.; Jeffery, S. N.;
Ji, W.; Johnson, M.; Johnson, J.; Johnson, P.; Jones, W. G.; Kaboth,
A. C.; Kamaha, A.; Kamdin, K.; Kasey, V.; Kazkaz, K.; Keefner, J.;
Khaitan, D.; Khaleeq, M.; Khazov, A.; Khromov, A. V.; Khurana, I.;
Kim, Y. D.; Kim, W. T.; Kocher, C. D.; Konovalov, A. M.; Korley,
L.; Korolkova, E. V.; Koyuncu, M.; Kras, J.; Kraus, H.; Kravitz,
S. W.; Krebs, H. J.; Kreczko, L.; Krikler, B.; Kudryavtsev, V. A.;
Kumpan, A. V.; Kyre, S.; Lambert, A. R.; Landerud, B.; Larsen, N. A.;
Laundrie, A.; Leason, E. A.; Lee, H. S.; Lee, J.; Lee, C.; Lenardo,
B. G.; Leonard, D. S.; Leonard, R.; Lesko, K. T.; Levy, C.; Li, J.;
Liu, Y.; Liao, J.; Liao, F. -T.; Lin, J.; Lindote, A.; Linehan, R.;
Lippincott, W. H.; Liu, R.; Liu, X.; Loniewski, C.; Lopes, M. I.;
López Paredes, B.; Lorenzon, W.; Lucero, D.; Luitz, S.; Lyle,
J. M.; Lynch, C.; Majewski, P. A.; Makkinje, J.; Malling, D. C.;
Manalaysay, A.; Manenti, L.; Mannino, R. L.; Marangou, N.; Markley,
D. J.; MarrLaundrie, P.; Martin, T. J.; Marzioni, M. F.; Maupin,
C.; McConnell, C. T.; McKinsey, D. N.; McLaughlin, J.; Mei, D. -M.;
Meng, Y.; Miller, E. H.; Minaker, Z. J.; Mizrachi, E.; Mock, J.;
Molash, D.; Monte, A.; Monzani, M. E.; Morad, J. A.; Morrison, E.;
Mount, B. J.; Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.;
Nehrkorn, C.; Nelson, H. N.; Nesbit, J.; Neves, F.; Nikkel, J. A.;
Nikoleyczik, J. A.; Nilima, A.; O'Dell, J.; Oh, H.; O'Neill, F. G.;
O'Sullivan, K.; Olcina, I.; Olevitch, M. A.; Oliver-Mallory, K. C.;
Oxborough, L.; Pagac, A.; Pagenkopf, D.; Pal, S.; Palladino, K. J.;
Palmaccio, V. M.; Palmer, J.; Pangilinan, M.; Patton, S. J.; Pease,
E. K.; Penning, B. P.; Pereira, G.; Pereira, C.; Peterson, I. B.;
Piepke, A.; Pierson, S.; Powell, S.; Preece, R. M.; Pushkin, K.;
Qie, Y.; Racine, M.; Ratcliff, B. N.; Reichenbacher, J.; Reichhart,
L.; Rhyne, C. A.; Richards, A.; Riffard, Q.; Rischbieter, G. R. C.;
Rodrigues, J. P.; Rose, H. J.; Rosero, R.; Rossiter, P.; Rucinski,
R.; Rutherford, G.; Rynders, D.; Saba, J. S.; Sabarots, L.; Santone,
D.; Sarychev, M.; Sazzad, A. B. M. R.; Schnee, R. W.; Schubnell, M.;
Scovell, P. R.; Severson, M.; Seymour, D.; Shaw, S.; Shutt, G. W.;
Shutt, T. A.; Silk, J. J.; Silva, C.; Skarpaas, K.; Skulski, W.; Smith,
A. R.; Smith, R. J.; Smith, R. E.; So, J.; Solmaz, M.; Solovov, V. N.;
Sorensen, P.; Sosnovtsev, V. V.; Stancu, I.; Stark, M. R.; Stephenson,
S.; Stern, N.; Stevens, A.; Stiegler, T. M.; Stifter, K.; Studley, R.;
Sumner, T. J.; Sundarnath, K.; Sutcliffe, P.; Swanson, N.; Szydagis,
M.; Tan, M.; Taylor, W. C.; Taylor, R.; Taylor, D. J.; Temples, D.;
Tennyson, B. P.; Terman, P. A.; Thomas, K. J.; Thomson, J. A.; Tiedt,
D. R.; Timalsina, M.; To, W. H.; Tomás, A.; Tope, T. E.; Tripathi,
M.; Tronstad, D. R.; Tull, C. E.; Turner, W.; Tvrznikova, L.; Utes,
M.; Utku, U.; Uvarov, S.; Va'vra, J.; Vacheret, A.; Vaitkus, A.;
Verbus, J. R.; Vietanen, T.; Voirin, E.; Vuosalo, C. O.; Walcott, S.;
Waldron, W. L.; Walker, K.; Wang, J. J.; Wang, R.; Wang, L.; Wang, Y.;
Watson, J. R.; Migneault, J.; Weatherly, S.; Webb, R. C.; Wei, W. -Z.;
While, M.; White, R. G.; White, J. T.; White, D. T.; Whitis, T. J.;
Wisniewski, W. J.; Wilson, K.; Witherell, M. S.; Wolfs, F. L. H.;
Wolfs, J. D.; Woodward, D.; Worm, S. D.; Xiang, X.; Xiao, Q.; Xu,
J.; Yeh, M.; Yin, J.; Young, I.; Zhang, C.
2019arXiv191009124T Altcode:
We describe the design and assembly of the LUX-ZEPLIN experiment,
a direct detection search for cosmic WIMP dark matter particles. The
centerpiece of the experiment is a large liquid xenon time projection
chamber sensitive to low energy nuclear recoils. Rejection of
backgrounds is enhanced by a Xe skin veto detector and by a liquid
scintillator Outer Detector loaded with gadolinium for efficient
neutron capture and tagging. LZ is located in the Davis Cavern at
the 4850' level of the Sanford Underground Research Facility in Lead,
South Dakota, USA. We describe the major subsystems of the experiment
and its key design features and requirements.
---------------------------------------------------------
Title: Exploring the Properties of Transverse Waves at the Base of
the Solar Wind
Authors: Weberg, Micah J.; Morton, Richard; McLaughlin, James; Laming,
Martin; Ko, Yuan-Kuen
2019shin.confE.173W Altcode:
Transverse (or ‘Alfvénic’) waves are commonly invoked by
theories and models to explain coronal heating and solar wind
acceleration. However, direct measurements are sparse and most of
what we know is derived from indirect proxies for wave activity. In
this study, we present a large, statistical study of transverse waves
directly observed in coronal plumes between May 2010 and May 2019
by SDO / AIA. The data was processed using an automated version of
the Northumbria University Wave Tracking Code (NUWT) and presents a
detailed picture of wave properties at the base of the solar wind. We
find that the bulk wave parameters within the time periods analysed
are largely consistent over most of a solar cycle. However, there is
some evidence for smaller-scale variations with height, latitude, and
over time periods of a few years. We will also explore the possibility
of frequency-dependant processes which may give limits on the height
at which wave dissipation, and thereby solar wind acceleration,
begins. Lastly, we will give estimates for the total energy flux
contained in the waves and discuss how it compares to the energy
required to accelerate the solar wind.
---------------------------------------------------------
Title: Damping of Propagating Kink Waves in the Solar Corona
Authors: Tiwari, Ajay K.; Morton, Richard J.; Régnier, Stéphane;
McLaughlin, James A.
2019ApJ...876..106T Altcode: 2019arXiv190408834T
Alfvénic waves have gained renewed interest since the existence of
ubiquitous propagating kink waves were discovered in the corona. It
has long been suggested that Alfvénic waves play an important role
in coronal heating and the acceleration of the solar wind. To this
effect, it is imperative to understand the mechanisms that enable their
energy to be transferred to the plasma. Mode conversion via resonant
absorption is believed to be one of the main mechanisms for kink wave
damping and it is considered to play a key role in the process of energy
transfer. This study examines the damping of propagating kink waves in
quiescent coronal loops using the Coronal Multi-channel Polarimeter. A
coherence-based method is used to track the Doppler velocity signal
of the waves, which enables us to investigate the spatial evolution of
velocity perturbations. The power ratio of outward to inward propagating
waves is used to estimate the associated damping lengths and quality
factors. To enable accurate estimates of these quantities, we provide
the first derivation of a likelihood function suitable for fitting
models to the ratio of two power spectra obtained from discrete Fourier
transforms. Maximum likelihood estimation is used to fit an exponential
damping model to the observed variation in power ratio as a function
of frequency. We confirm earlier indications that propagating kink
waves are undergoing frequency-dependent damping. Additionally, we find
that the rate of damping decreases, or equivalently the damping length
increases, for longer coronal loops that reach higher in the corona.
---------------------------------------------------------
Title: 3D WKB solution for fast magnetoacoustic wave behaviour within
a separatrix dome containing a coronal null point
Authors: McLaughlin, James A.; Thurgood, Jonathan O.; Botha, Gert
J. J.; Wiggs, Joshua A.
2019MNRAS.484.1390M Altcode: 2019MNRAS.tmp..133M
The propagation of the fast magnetoacoustic wave is studied within a
magnetic topology containing a 3D coronal null point whose fan field
lines form a dome. The topology is constructed from a magnetic dipole
embedded within a global uniform field. This study aims to improve the
understanding of how magnetohydrodynamics (MHD) waves propagate through
inhomogeneous media, specifically in a medium containing an isolated 3D
magnetic null point. We consider the linearized MHD equations for an
inhomogeneous, ideal, cold plasma. The equations are solved utilizing
the WKB approximation and Charpit's Method. We find that for a planar
fast wave generated below the null point, the resultant propagation is
strongly dependent upon initial location and that there are two main
behaviours: the majority of the wave escapes the null (experiencing
different severities of refraction depending upon the interplay with the
equilibrium Alfvén-speed profile) or, alternatively, part of the wave
is captured by the coronal null point (for elements generated within
a specific critical radius about the spine and on the z = 0 plane). We
also generalize the magnetic topology and find that the height of the
null determines the amount of wave that is captured. We conclude that
for a wavefront generated below the null point, nulls at a greater
height can trap proportionally less of the corresponding wave energy.
---------------------------------------------------------
Title: On the periodicity of linear and nonlinear oscillatory
reconnection
Authors: Thurgood, J. O.; Pontin, D. I.; McLaughlin, J. A.
2019A&A...621A.106T Altcode: 2018arXiv181108831T
Context. An injection of energy towards a magnetic null point can
drive reversals of current-sheet polarity leading to time-dependent,
oscillatory reconnection (OR), which may explain periodic phenomena
generated when reconnection occurs in the solar atmosphere. However, the
details of what controls the period of these current-sheet oscillations
in realistic systems is poorly understood, despite being of crucial
importance in assessing whether a specific model of OR can account for
observed periodic behaviour. <BR /> Aims: This paper aims to highlight
that different types of reconnection reversal are supported about
null points, and that these can be distinct from the oscillation
in the closed-boundary, linear systems considered by a number of
authors in the 1990s. In particular, we explore the features of a
nonlinear oscillation local to the null point, and examine the effect
of resistivity and perturbation energy on the period, contrasting it to
the linear, closed-boundary case. <BR /> Methods: Numerical simulations
of the single-fluid, resistive MHD equations are used to investigate the
effects of plasma resistivity and perturbation energy upon the resulting
OR. <BR /> Results: It is found that for small perturbations that behave
linearly, the inverse Lundquist number dictates the period, provided
the perturbation energy (i.e. the free energy) is small relative to
the inverse Lundquist number defined on the boundary, regardless of
the broadband structure of the initial perturbation. However, when the
perturbation energy exceeds the threshold required for "nonlinear"
null collapse to occur, a complex oscillation of the magnetic
field is produced which is, at most, only weakly-dependent on the
resistivity. The resultant periodicity is instead strongly influenced
by the amount of free energy, with more energetic perturbations
producing higher-frequency oscillations. <BR /> Conclusions: Crucially,
with regards to typical solar-based and astrophysical-based input
energies, we demonstrate that the majority far exceed the threshold
for nonlinearity to develop. This substantially alters the properties
and periodicity of both null collapse and subsequent OR. Therefore,
nonlinear regimes of OR should be considered in solar and astrophysical
contexts. <P />The movie associated to Fig. 3 is available at <A
href="https://www.aanda.org/10.1051/0004-6361/201834369/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: A basal contribution from p-modes to the Alfvénic wave flux
in the Sun's corona
Authors: Morton, R. J.; Weberg, M. J.; McLaughlin, J. A.
2019NatAs...3..223M Altcode: 2019arXiv190203811M; 2019NatAs.tmp..196M
Many cool stars possess complex magnetic fields<SUP>1</SUP> that are
considered to undertake a central role in the structuring and energizing
of their atmospheres<SUP>2</SUP>. Alfvénic waves are thought to
make a critical contribution to energy transfer along these magnetic
fields, with the potential to heat plasma and accelerate stellar
winds<SUP>3-5</SUP>. Despite Alfvénic waves having been identified
in the Sun's atmosphere, the nature of the basal wave energy flux
is poorly understood. It is generally assumed that the associated
Poynting flux is generated solely in the photosphere and propagates
into the corona, typically through the continuous buffeting of magnetic
fields by turbulent convective cells<SUP>4,6,7</SUP>. Here, we provide
evidence that the Sun's internal acoustic modes also contribute to
the basal flux of Alfvénic waves, delivering a spatially ubiquitous
input to the coronal energy balance that is sustained over the solar
cycle. Alfvénic waves are thus a fundamental feature of the Sun's
corona. Acknowledging that internal acoustic modes have a key role
in injecting additional Poynting flux into the upper atmospheres
of Sun-like stars has potentially significant consequences for the
modelling of stellar coronae and winds.
---------------------------------------------------------
Title: Predictions of DKIST/DL-NIRSP Observations for an Off-limb
Kink-unstable Coronal Loop
Authors: Snow, B.; Botha, G. J. J.; Scullion, E.; McLaughlin, J. A.;
Young, P. R.; Jaeggli, S. A.
2018ApJ...863..172S Altcode: 2018arXiv180704972S
Synthetic intensity maps are generated from a 3D kink-unstable flux
rope simulation using several DKIST/DL-NIRSP spectral lines to make
a prediction of the observational signatures of energy transport and
release. The reconstructed large field-of-view intensity mosaics and
single tile sit-and-stare high-cadence image sequences show detailed,
fine-scale structure and exhibit signatures of wave propagation,
redistribution of heat, flows, and fine-scale bursts. These fine-scale
bursts are present in the synthetic Doppler velocity maps and can be
interpreted as evidence for small-scale magnetic reconnection at the
loop boundary. The spectral lines reveal the different thermodynamic
structures of the loop, with the hotter lines showing the loop
interior and braiding and the cooler lines showing the radial edges
of the loop. The synthetic observations of DL-NIRSP are found to
preserve the radial expansion, and hence the loop radius can be
measured accurately. The electron number density can be estimated
using the intensity ratio of the Fe XIII lines at 10747 and 10798
Å. The estimated density from this ratio is correct to within ±10%
during the later phases of the evolution; however, it is less accurate
initially when line-of-sight density inhomogeneities contribute to the
Fe XIII intensity, resulting in an overprediction of the density by
≈30%. The identified signatures are all above a conservative estimate
for instrument noise and therefore will be detectable. In summary, we
have used forward modeling to demonstrate that the coronal off-limb
mode of DKIST/DL-NIRSP will be able to detect multiple independent
signatures of a kink-unstable loop and observe small-scale transient
features including loop braiding/twisting and small-scale reconnection
events occurring at the radial edge of the loop.
---------------------------------------------------------
Title: Resistively-limited current sheet implosions in planar
anti-parallel (1D) and null-point containing (2D) magnetic field
geometries
Authors: Thurgood, Jonathan O.; Pontin, David I.; McLaughlin, James A.
2018PhPl...25g2105T Altcode: 2018arXiv180608157T
Implosive formation of current sheets is a fundamental plasma
process. Previous studies focused on the early time evolution, while
here our primary aim is to explore the longer-term evolution, which
may be critical for determining the efficiency of energy release. To
address this problem, we investigate two closely related problems,
namely: (i) 1D, pinched anti-parallel magnetic fields and (ii) 2D, null
point containing fields which are locally imbalanced ("null-collapse"
or "X-point collapse"). Within the framework of resistive MHD, we
simulate the full nonlinear evolution through three distinct phases:
the initial implosion, its eventual halting mechanism, and subsequent
evolution post-halting. In a parameter study, we find that the scaling
with resistivity of current sheet properties at the halting time is in
good agreement—in both geometries—with that inferred from a known 1D
similarity solution. We find that the halting of the implosions occurs
rapidly after reaching the diffusion scale by sudden Ohmic heating of
the dense plasma within the current sheet, which provides a pressure
gradient sufficient to oppose further collapse and decelerate the
converging flow. This back-pressure grows to exceed that required for
force balance and so the post-implosion evolution is characterised by
the consequences of the current sheet "bouncing" outwards. These are:
(i) the launching of propagating fast MHD waves (shocks) outwards and
(ii) the width-wise expansion of the current sheet itself. The expansion
is only observed to stall in the 2D case, where the pressurisation
is relieved by outflow in the reconnection jets. In the 2D case, we
quantify the maximum amount of current sheet expansion as it scales
with resistivity and analyse the structure of the reconnection region,
which forms post-expansion, replete with Petschek-type slow shocks
and fast termination shocks.
---------------------------------------------------------
Title: Implosive Collapse about Magnetic Null Points: A Quantitative
Comparison between 2D and 3D Nulls
Authors: Thurgood, Jonathan O.; Pontin, David I.; McLaughlin, James A.
2018ApJ...855...50T Altcode: 2018arXiv180207076T
Null collapse is an implosive process whereby MHD waves focus their
energy in the vicinity of a null point, forming a current sheet and
initiating magnetic reconnection. We consider, for the first time,
the case of collapsing 3D magnetic null points in nonlinear, resistive
MHD using numerical simulation, exploring key physical aspects of the
system as well as performing a detailed parameter study. We find that
within a particular plane containing the 3D null, the plasma and current
density enhancements resulting from the collapse are quantitatively
and qualitatively as per the 2D case in both the linear and nonlinear
collapse regimes. However, the scaling with resistivity of the 3D
reconnection rate—which is a global quantity—is found to be less
favorable when the magnetic null point is more rotationally symmetric,
due to the action of increased magnetic back-pressure. Furthermore,
we find that, with increasing ambient plasma pressure, the collapse
can be throttled, as is the case for 2D nulls. We discuss this
pressure-limiting in the context of fast reconnection in the solar
atmosphere and suggest mechanisms by which it may be overcome. We
also discuss the implications of the results in the context of
null collapse as a trigger mechanism of Oscillatory Reconnection,
a time-dependent reconnection mechanism, and also within the wider
subject of wave-null point interactions. We conclude that, in general,
increasingly rotationally asymmetric nulls will be more favorable in
terms of magnetic energy release via null collapse than their more
symmetric counterparts.
---------------------------------------------------------
Title: Modelling Quasi-Periodic Pulsations in Solar and Stellar Flares
Authors: McLaughlin, J. A.; Nakariakov, V. M.; Dominique, M.; Jelínek,
P.; Takasao, S.
2018SSRv..214...45M Altcode: 2018arXiv180204180M
Solar flare emission is detected in all EM bands and variations in flux
density of solar energetic particles. Often the EM radiation generated
in solar and stellar flares shows a pronounced oscillatory pattern, with
characteristic periods ranging from a fraction of a second to several
minutes. These oscillations are referred to as quasi-periodic pulsations
(QPPs), to emphasise that they often contain apparent amplitude and
period modulation. We review the current understanding of quasi-periodic
pulsations in solar and stellar flares. In particular, we focus on
the possible physical mechanisms, with an emphasis on the underlying
physics that generates the resultant range of periodicities. These
physical mechanisms include MHD oscillations, self-oscillatory
mechanisms, oscillatory reconnection/reconnection reversal, wave-driven
reconnection, two loop coalescence, MHD flow over-stability, the
equivalent LCR-contour mechanism, and thermal-dynamical cycles. We
also provide a histogram of all QPP events published in the literature
at this time. The occurrence of QPPs puts additional constraints on
the interpretation and understanding of the fundamental processes
operating in flares, e.g. magnetic energy liberation and particle
acceleration. Therefore, a full understanding of QPPs is essential in
order to work towards an integrated model of solar and stellar flares.
---------------------------------------------------------
Title: Onset of 2D magnetic reconnection in the solar photosphere,
chromosphere, and corona
Authors: Snow, B.; Botha, G. J. J.; McLaughlin, J. A.; Hillier, A.
2018A&A...609A.100S Altcode: 2017arXiv171100683S
<BR /> Aims: We aim to investigate the onset of 2D time-dependent
magnetic reconnection that is triggered using an external (non-local)
velocity driver located away from, and perpendicular to, an
equilibrium Harris current sheet. Previous studies have typically
utilised an internal trigger to initiate reconnection, for example
initial conditions centred on the current sheet. Here, an external
driver allows for a more naturalistic trigger as well as the study
of the earlier stages of the reconnection start-up process. <BR />
Methods: Numerical simulations solving the compressible, resistive
magnetohydrodynamic (MHD) equations were performed to investigate the
reconnection onset within different atmospheric layers of the Sun,
namely the corona, chromosphere and photosphere. <BR /> Results: A
reconnecting state is reached for all atmospheric heights considered,
with the dominant physics being highly dependent on atmospheric
conditions. The coronal case achieves a sharp rise in electric field
(indicative of reconnection) for a range of velocity drivers. For the
chromosphere, we find a larger velocity amplitude is required to trigger
reconnection (compared to the corona). For the photospheric environment,
the electric field is highly dependent on the inflow speed; a sharp
increase in electric field is obtained only as the velocity entering
the reconnection region approaches the Alfvén speed. Additionally,
the role of ambipolar diffusion is investigated for the chromospheric
case and we find that the ambipolar diffusion alters the structure
of the current density in the inflow region. <BR /> Conclusions: The
rate at which flux enters the reconnection region is controlled by
the inflow velocity. This determines all aspects of the reconnection
start-up process, that is, the early onset of reconnection is dominated
by the advection term in Ohm's law in all atmospheric layers. A lower
plasma-β enhances reconnection and creates a large change in the
electric field. A high plasma-β hinders the reconnection, yielding a
sharp rise in the electric field only when the velocity flowing into
the reconnection region approaches the local Alfvén speed.
---------------------------------------------------------
Title: An Automated Algorithm for Identifying and Tracking Transverse
Waves in Solar Images
Authors: Weberg, Micah J.; Morton, Richard J.; McLaughlin, James A.
2018ApJ...852...57W Altcode: 2018arXiv180704842W
Recent instrumentation has demonstrated that the solar atmosphere
supports omnipresent transverse waves, which could play a key role
in energizing the solar corona. Large-scale studies are required
in order to build up an understanding of the general properties
of these transverse waves. To help facilitate this, we present an
automated algorithm for identifying and tracking features in solar
images and extracting the wave properties of any observed transverse
oscillations. We test and calibrate our algorithm using a set of
synthetic data, which includes noise and rotational effects. The
results indicate an accuracy of 1%-2% for displacement amplitudes
and 4%-10% for wave periods and velocity amplitudes. We also apply
the algorithm to data from the Atmospheric Imaging Assembly on board
the Solar Dynamics Observatory and find good agreement with previous
studies. Of note, we find that 35%-41% of the observed plumes exhibit
multiple wave signatures, which indicates either the superposition
of waves or multiple independent wave packets observed at different
times within a single structure. The automated methods described
in this paper represent a significant improvement on the speed and
quality of direct measurements of transverse waves within the solar
atmosphere. This algorithm unlocks a wide range of statistical studies
that were previously impractical.
---------------------------------------------------------
Title: Annual Properties of Transverse Waves in the Corona over most
of Solar Cycle 24
Authors: Weberg, M. J.; Morton, R. J.; McLaughlin, J. A.
2017AGUFMSH42B..07W Altcode:
Waves are an omnipresent feature in heliophysical plasmas. In
particular, transverse (or "Alfvénic") waves have been observed at a
wide range of spatial and temporal scales within the corona and solar
wind. These waves play a key role in transporting energy through the
solar atmosphere and are also thought to contribute to the heating and
acceleration of the solar wind. Previous studies of low-frequency (<
10 mHz) transverse waves in coronal loops and polar plumes have provided
tantalizing glimpses at specific time periods, however few, if any,
systematic studies have been performed spanning long time scales. In
this study, we combine recent advancements in the automated detection
and measurement of low-frequency transverse waves with over 7 years
of SDO / AIA data to provide a detailed picture of coronal transverse
waves in polar plumes and, for the first time, begin to examine their
long-term behaviour. We measure waves at three different heights in
each of eight, four-hour periods spanning May 2010 - May 2017. We
find that the bulk wave parameters within these 24 regions are largely
consistent over most of a solar cycle. However, there is some evidence
for smaller-scale variations both with height and over time periods
of a few years. We also discuss total energy flux estimations based
on the full wave power spectra, which yields a more nuanced picture
than previous values based on summary statistics. Overall, this work
expands our view of wave processes in the corona and is relevant to
both theoretical and modelling considerations of energy transport
within the solar atmosphere. Crucially, these initial results suggest
that the energy flux provided by the low-frequency transverse waves
varies little over the solar cycle, potentially indicating that the
waves provide a consistent source of energy to the corona and beyond.
---------------------------------------------------------
Title: Three-dimensional Oscillatory Reconnection
Authors: Thurgood, Jonathan; Pontin, David; McLaughlin, James
2017shin.confE..88T Altcode:
Here we detail the dynamic evolution of localised reconnection regions
about three-dimensional (3D) magnetic null points by using numerical
simulation. We demonstrate for the first time that reconnection
triggered by the localised collapse of a 3D null point due to an
external MHD wave involves a self-generated oscillation, whereby the
current sheet and outflow jets undergo a reconnection reversal process
during which back-pressure formation at the jet heads acts to prise
open the collapsed field before overshooting the equilibrium into an
opposite-polarity configuration. The discovery that reconnection at
fully 3D nulls can proceed naturally in a time-dependent and periodic
fashion is suggestive that oscillatory reconnection mechanisms may play
a role in explaining periodicity in astrophysical phenomena associated
with magnetic reconnection, such as the observed quasi-periodicity of
solar and stellar flare emission. Furthermore, we find a consequence
of oscillatory reconnection is the generation of a plethora of
freely-propagating MHD waves which escape the vicinity of the
reconnection region.
---------------------------------------------------------
Title: Three-dimensional Oscillatory Magnetic Reconnection
Authors: Thurgood, Jonathan O.; Pontin, David I.; McLaughlin, James A.
2017ApJ...844....2T Altcode: 2017arXiv170609662T
Here we detail the dynamic evolution of localized reconnection regions
about 3D magnetic null points using numerical simulation. We demonstrate
for the first time that reconnection triggered by the localized collapse
of a 3D null point that is due to an external magnetohydrodynamic
(MHD) wave involves a self-generated oscillation, whereby the current
sheet and outflow jets undergo a reconnection reversal process
during which back-pressure formation at the jet heads acts to prise
open the collapsed field before overshooting the equilibrium into an
opposite-polarity configuration. The discovery that reconnection at
fully 3D nulls can proceed naturally in a time-dependent and periodic
fashion suggests that oscillatory reconnection mechanisms may play a
role in explaining periodicity in astrophysical phenomena associated
with magnetic reconnection, such as the observed quasi-periodicity
of solar and stellar flare emission. Furthermore, we find that
a consequence of oscillatory reconnection is the generation of a
plethora of freely propagating MHD waves that escape the vicinity of
the reconnection region.
---------------------------------------------------------
Title: Project SunbYte: solar astronomy on a budget
Authors: Alvarez Gonzalez, F.; Badilita, A. -M.; Baker, A.; Cho,
Y. -H.; Dhot, N.; Fedun, V.; Hare, C.; He, T.; Hobbs, M.; Javed,
M.; Lovesey, H.; Lord, C.; Panoutsos, G.; Permyakov, A.; Pope, S.;
Portnell, M.; Rhodes, L.; Sharma, R.; Taras, P.; Taylor, J.; Tilbrook,
R.; Verth, G.; Wrigley, S. N.; Yaqoob, M.; Cook, R.; McLaughlin, J.;
Morton, R.; Scullion, E.; Shelyag, S.; Hamilton, A.; Zharkov, S.;
Jess, D.; Wrigley, M.
2017A&G....58d2.24A Altcode:
The Sheffield University Nova Balloon Lifted Solar Telescope (SunbYte)
is a high-altitude balloon experiment devised and run largely by
students at the University of Sheffield, and is scheduled for launch
in October 2017. It was the only UK project in 2016 to be selected for
the balloon side of the Swedish-German student programme REXUS/BEXUS
(Rocket and Balloon Experiments for University Students; see box on
p2.25). The success of the SunbYte team in the REXUS/BEXUS selection
process is an unprecedented opportunity for the students to gain
valuable experience working in the space engineering industry, using
their theoretical knowledge and networking with students and technology
companies from all over Europe.
---------------------------------------------------------
Title: Erosion and Basin Modification of Smaller Complex Craters in
the Isidis Region, Mars
Authors: McLaughlin, J. A.; Davatzes, A. K.
2017LPI....48.1190M Altcode:
Trends of features found / In martian crater basins / Rim degradation.
---------------------------------------------------------
Title: Automating Direct Observations of Transverse Waves in the
Solar Corona
Authors: Weberg, M. J.; Morton, R. J.; McLaughlin, J. A.
2016AGUFMSH21E2576W Altcode:
A multitude of MHD waves have been observed at a large range of scales
in the solar atmosphere. According to theories and models, transverse
(or "Alfvénic") waves are a viable mechanism for both heating and
accelerating the solar wind and may also drive certain elemental
fractionation processes in the chromosphere and corona. However,
direct measurements of transverse waves in polar plumes (Thurgood
et al. 2014) have raised some questions concerning the total energy
carried by the waves and whether or not it is sufficient to be a
primary driver of either solar wind heating or acceleration. In
this work we build upon on the framework of Morton & McLaughlin
(2013) and Thurgood et al. (2014) and extend the capabilities of the
Northumbria University Wave Tracking (NUWT) code. In particular, we
present an automated method of detecting and quantifying transverse
waves in polar coronal holes. With the application of Fourier analysis
methods, we investigate the superposition of multiple waves propagating
along individual structures and, additionally, examine multi-variate
relationships that may exist between wave parameters. We report the
distributions of wave parameters for hundreds of waves observed using
data from the 171 Å channel of SDO / AIA at select times throughout
the solar cycle. Finally, we discuss how the measured average wave
energy compares to theoretical predictions. The methods described in
this research can be easily applied to other instruments, both space-
and ground-based, and the observations of wave parameters and energetics
place important constraints on wave-driven models of the solar corona.
---------------------------------------------------------
Title: Exploring Coronal Dynamics: A Next Generation Solar Physics
Mission white paper
Authors: Morton, R. J.; Scullion, E.; Bloomfield, D. S.; McLaughlin,
J. A.; Regnier, S.; McIntosh, S. W.; Tomczyk, S.; Young, P.
2016arXiv161106149M Altcode:
Determining the mechanisms responsible for the heating of the
coronal plasma and maintaining and accelerating the solar wind
are long standing goals in solar physics. There is a clear need to
constrain the energy, mass and momentum flux through the solar corona
and advance our knowledge of the physical process contributing to
these fluxes. Furthermore, the accurate forecasting of Space Weather
conditions at the near-Earth environment and, more generally, the
plasma conditions of the solar wind throughout the heliosphere, require
detailed knowledge of these fluxes in the near-Sun corona. Here we
present a short case for a space-based imaging-spectrometer coronagraph,
which will have the ability to provide synoptic information on the
coronal environment and provide strict constraints on the mass, energy,
and momentum flux through the corona. The instrument would ideally
achieve cadences of $\sim10$~s, spatial resolution of 1" and observe the
corona out to 2~$R_{\sun}$. Such an instrument will enable significant
progress in our understanding of MHD waves throughout complex plasmas,
as well as potentially providing routine data products to aid Space
Weather forecasting.
---------------------------------------------------------
Title: 3D WKB solution for fast magnetoacoustic wave behaviour around
an X-line
Authors: McLaughlin, J. A.; Botha, G. J. J.; Régnier, S.; Spoors,
D. L.
2016A&A...591A.103M Altcode: 2016arXiv160702379M
Context. We study the propagation of a fast magnetoacoustic wave in
a 3D magnetic field created from two magnetic dipoles. The magnetic
topology contains an X-line. <BR /> Aims: We aim to contribute to the
overall understanding of MHD wave propagation within inhomogeneous
media, specifically around X-lines. <BR /> Methods: We investigate the
linearised, 3D MHD equations under the assumptions of ideal and cold
plasma. We utilise the WKB approximation and Charpit's method during
our investigation. <BR /> Results: It is found that the behaviour
of the fast magnetoacoustic wave is entirely dictated by the local,
inhomogeneous, equilibrium Alfvén speed profile. All parts of the
wave experience refraction during propagation, where the magnitude of
the refraction effect depends on the location of an individual wave
element within the inhomogeneous magnetic field. The X-line, along
which the Alfvén speed is identically zero, acts as a focus for the
refraction effect. There are two main types of wave behaviour: part
of the wave is either trapped by the X-line or escapes the system, and
there exists a critical starting region around the X-line that divides
these two types of behaviour. For the set-up investigated, it is found
that 15.5% of the fast wave energy is trapped by the X-line. <BR />
Conclusions: We conclude that linear, β = 0 fast magnetoacoustic waves
can accumulate along X-lines and thus these will be specific locations
of fast wave energy deposition and thus preferential heating. The work
here highlights the importance of understanding the magnetic topology
of a system. We also demonstrate how the 3D WKB technique described
in this paper can be applied to other magnetic configurations.
---------------------------------------------------------
Title: Nuwt: Northumbria University Wave Tracking (Nuwt) Code
Authors: Morton, Richard J.; Mooroogen, Krishna; McLaughlin, James A.
2016zndo.....49563M Altcode:
This is the first release of the Northumbria University Wave Tracking
(NUWT) code (in IDL). The code is primarily designed to analyse
transverse waves along curvilinear features in solar imaging data,
however, the underlying operations will work on any images. Tutorials
and videos are included with the release.
---------------------------------------------------------
Title: Behaviour of Magnetoacoustic Waves in the Neighbourhood of
a Two-Dimensional Null Point: Initially Cylindrically Symmetric
Perturbations
Authors: McLaughlin, J. A.
2016JApA...37....2M Altcode: 2016arXiv160702363M
The propagation of magnetoacoustic waves in the neighbourhood of a 2D
null point is investigated for both β=0 and β ≠ 0 plasmas. Previous
work has shown that the Alfvén speed, here v <SUB> A </SUB>∝ r, plays
a vital role in such systems and so a natural choice is to switch to
polar coordinates. For β=0 plasma, we derive an analytical solution
for the behaviour of the fast magnetoacoustic wave in terms of the
Klein-Gordon equation. We also solve the system with a semi-analytical
WKB approximation which shows that the β=0 wave focuses on the null
and contracts around it but, due to exponential decay, never reaches
the null in a finite time. For the β ≠ 0 plasma, we solve the system
numerically and find the behaviour to be similar to that of the β=0
system at large radii, but completely different close to the null. We
show that for an initially cylindrically-symmetric fast magnetoacoustic
wave perturbation, there is a decrease in wave speed along the
separatrices and so the perturbation starts to take on a quasi-diamond
shape; with the corners located along the separatrices. This is due
to the growth in pressure gradients that reach a maximum along the
separatrices, which in turn reduces the acceleration of the fast wave
along the separatrices leading to a deformation of the wave morphology.
---------------------------------------------------------
Title: First Direct Measurements of Transverse Waves in Solar Polar
Plumes Using SDO/AIA
Authors: Thurgood, J. O.; Morton, R. J.; McLaughlin, J. A.
2014ApJ...790L...2T Altcode: 2014arXiv1406.5348T
There is intense interest in determining the precise contribution of
Alfvénic waves propagating along solar structures to the problems
of coronal heating and solar wind acceleration. Since the launch of
SDO/AIA, it has been possible to resolve transverse oscillations in
off-limb solar polar plumes and recently McIntosh et al. concluded
that such waves are energetic enough to play a role in heating the
corona and accelerating the fast solar wind. However, this result is
based on comparisons to Monte Carlo simulations and confirmation via
direct measurements is still outstanding. Thus, this Letter reports
on the first direct measurements of transverse wave motions in solar
polar plumes. Over a four hour period, we measure the transverse
displacements, periods, and velocity amplitudes of 596 distinct
oscillations observed in the 171 Å channel of SDO/AIA. We find a
broad range of non-uniformly distributed parameter values which are
well described by log-normal distributions with peaks at 234 km,
121 s, and 8 km s<SUP>-1</SUP>, and mean and standard deviations of
407 ± 297 km, 173 ± 118 s, and 14 ± 10 km s<SUP>-1</SUP>. Within
standard deviations, our direct measurements are broadly consistent
with previous results. However, accounting for the whole of our observed
non-uniform parameter distribution we calculate an energy flux of 9-24
W m<SUP>-2</SUP>, which is 4-10 times below the energy requirement for
solar wind acceleration. Hence, our results indicate that transverse
magnetohydrodynamic waves as resolved by SDO/AIA cannot be the dominant
energy source for fast solar wind acceleration in the open-field corona.
---------------------------------------------------------
Title: High-resolution Observations of Active Region Moss and its
Dynamics
Authors: Morton, R. J.; McLaughlin, J. A.
2014ApJ...789..105M Altcode: 2014arXiv1405.5694M
The High Resolution Coronal Imager has provided the sharpest view
of the EUV corona to date. In this paper, we exploit its impressive
resolving power to provide the first analysis of the fine-scale
structure of moss in an active region. The data reveal that the moss
is made up of a collection of fine threads that have widths with a
mean and standard deviation of 440 ± 190 km (FWHM). The brightest
moss emission is located at the visible head of the fine-scale
structure and the fine structure appears to extend into the lower
solar atmosphere. The emission decreases along the features, implying
that the lower sections are most likely dominated by cooler transition
region plasma. These threads appear to be the cool, lower legs of the
hot loops. In addition, the increased resolution allows for the first
direct observation of physical displacements of the moss fine structure
in a direction transverse to its central axis. Some of these transverse
displacements demonstrate periodic behavior, which we interpret as a
signature of kink (Alfvénic) waves. Measurements of the properties
of the transverse motions are made and the wave motions have means
and standard deviations of 55 ± 37 km for the transverse displacement
amplitude, 77 ± 33 s for the period, and 4.7 ± 2.5 km s<SUP>-1</SUP>
for the velocity amplitude. The presence of waves in the transition
region of hot loops could have important implications for the heating
of active regions.
---------------------------------------------------------
Title: High-resolution observations of active region moss and its
dynamics
Authors: Morton, Richard; McLaughlin, James
2014cosp...40E2181M Altcode:
The High resolution Coronal Imager (Hi-C) has provided the sharpest
view of the EUV corona to date. I will present results that exploit
its impressive resolving power to provide the first analysis of the
fine-scale structure of moss in an active region. The data reveal
that the moss is made up of a collection of fine threads that have
widths ranging between 400-1000 km. These fine-scale structures are
connected to the bright moss and appear to extend into the lower solar
atmosphere. The emission decreases along the features implying the
lower sections are most likely dominated by cooler transition region
plasma. These threads appear to be the cool, lower legs of the hot
loops. The increased resolution also allows for the first direct
observation of physical displacements of the moss fine-structure in
a direction transverse to its central axis. Some of these transverse
displacements demonstrate periodic behaviour, which we interpret as
a signature of kink (Alfvénic) waves. The presence of waves in the
transition region of hot loops could have important implications for
the heating of active regions.
---------------------------------------------------------
Title: On Ponderomotive Effects Induced by Alfvén Waves in
Inhomogeneous 2.5D MHD Plasmas
Authors: Thurgood, J. O.; McLaughlin, J. A.
2013SoPh..288..205T Altcode: 2013arXiv1302.4340T
Where spatial gradients in the amplitude of an Alfvén wave are
non-zero, a nonlinear magnetic-pressure gradient acts upon the medium
(commonly referred to as the ponderomotive force). We investigate the
nature of such a force in inhomogeneous 2.5D MHD plasmas by analysing
source terms in the nonlinear wave equations for the general case of
inhomogeneous B and ρ, and consider supporting nonlinear numerical
simulations. Our equations indicate that there are two distinct classes
of ponderomotive effect induced by Alfvén waves in general 2.5D MHD,
each with both a longitudinal and transverse manifestation. i) Geometric
effects: Gradients in the pulse geometry relative to the background
magnetic field cause the wave to sustain cospatial disturbances, the
longitudinal and transverse daughter disturbances - where we report on
the transverse disturbance for the first time. ii) ∇(c<SUB>A</SUB>)
effects: Where a pulse propagates through an inhomogeneous region
(where the gradients in the Alfvén-speed profile c<SUB>A</SUB> are
non-zero), the nonlinear magnetic-pressure gradient acts to accelerate
the plasma. Transverse gradients (phase mixing regions) excite
independently propagating fast magnetoacoustic waves (generalising
the result of Nakariakov, Roberts, and Murawski (Solar Phys.175, 93,
1997)) and longitudinal gradients (longitudinally dispersive regions)
perturb along the field (thus creating static disturbances in β=0,
and slow waves in β≠0). We additionally demonstrate that mode
conversion due the nonlinear Lorentz force is a one-way process, and
does not act as a mechanism to nonlinearly generate Alfvén waves due to
propagating magnetoacoustic waves. We conclude that these ponderomotive
effects are induced by an Alfvén wave propagating in any MHD medium,
and have the potential to have significant consequences on the dynamics
of energy transport and aspects of dissipation provided the system is
sufficiently nonlinear and inhomogeneous.
---------------------------------------------------------
Title: 3D Alfvén wave behaviour about proper and improper magnetic
null points
Authors: Thurgood, J. O.; McLaughlin, J. A.
2013A&A...558A.127T Altcode: 2013arXiv1307.7001T
Context. Magnetohydrodynamic (MHD) waves and magnetic null points
are both prevalent in many astrophysical plasmas, including the
solar atmosphere. Interaction between waves and null points has been
implicated as a possible mechanism for localised heating events. <BR
/> Aims: Here we investigate the transient behaviour of the Alfvén
wave about fully 3D proper and improper magnetic null points. <BR />
Methods: We introduce an Alfvén wave into the vicinity of both proper
and improper null points by numerically solving the ideal, β = 0 MHD
equations using the LARE3D code. A magnetic fieldline and flux-based
coordinate system permits the isolation of resulting wave modes and
the analysis of their interaction. <BR /> Results: We find that the
Alfvén wave propagates throughout the region and accumulates near the
fan-plane, causing current build up. For different values of null point
eccentricity, the qualitative behaviour changes only by the imposition
of anisotropic pulse dilation, owing to the differing rates at which
fieldlines diverge from the spine. For all eccentricities, we find that
the fast and Alfvén waves are linearly decoupled. During the driving
phase, an independently propagating fast wave is nonlinearly generated
owing to the ponderomotive force. Subsequently, no further excitation of
fast waves occurs. <BR /> Conclusions: We find that the key aspects of
the theory of Alfvén waves about 2D null points extends intuitively to
the fully 3D case; i.e. the wave propagates along fieldlines and thus
accumulates at predictable parts of the topology. We also highlight
that unlike in the 2D case, in 3D Alfvén-wave pulses are always
toroidal, and thus any aspects of 2D Alfvén-wave-null models that
are pulse-geometry specific must be reconsidered in 3D.
---------------------------------------------------------
Title: Phase Mixing of Alfvén Waves Near a 2D Magnetic Null Point
Authors: McLaughlin, J. A.
2013JApA...34..223M Altcode: 2014arXiv1407.1743M; 2013JApA..tmp...23M
The propagation of linear Alfvén wave pulses in an inhomogeneous plasma
near a 2D coronal null point is investigated. When a uniform plasma
density is considered, it is seen that an initially planar Alfvén
wavefront remains planar, despite the varying equilibrium Alfvén
speed, and that all the wave collects at the separatrices. Thus,
in the non-ideal case, these Alfvénic disturbances preferentially
dissipate their energy at these locations. For a non-uniform equilibrium
density, it is found that the Alfvén wavefront is significantly
distorted away from the initially planar geometry, inviting the
possibility of dissipation due to phase mixing. Despite this however,
we conclude that for the Alfvén wave, current density accumulation
and preferential heating still primarily occur at the separatrices,
even when an extremely non-uniform density profile is considered.
---------------------------------------------------------
Title: Hi-C and AIA observations of transverse magnetohydrodynamic
waves in active regions (Corrigendum)
Authors: Morton, R. J.; McLaughlin, J. A.
2013A&A...556C...1M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Non-symmetric magnetohydrostatic equilibria: a multigrid
approach
Authors: MacTaggart, D.; Elsheikh, A.; McLaughlin, J. A.; Simitev,
R. D.
2013A&A...556A..40M Altcode: 2013arXiv1307.6720M
<BR /> Aims: Linear magnetohydrostatic (MHS) models of solar magnetic
fields balance plasma pressure gradients, gravity and Lorentz
forces where the current density is composed of a linear force-free
component and a cross-field component that depends on gravitational
stratification. In this paper, we investigate an efficient numerical
procedure for calculating such equilibria. <BR /> Methods: The MHS
equations are reduced to two scalar elliptic equations - one on the
lower boundary and the other within the interior of the computational
domain. The normal component of the magnetic field is prescribed on the
lower boundary and a multigrid method is applied on both this boundary
and within the domain to find the poloidal scalar potential. Once
solved to a desired accuracy, the magnetic field, plasma pressure and
density are found using a finite difference method. <BR /> Results:
We investigate the effects of the cross-field currents on the linear
MHS equilibria. Force-free and non-force-free examples are given to
demonstrate the numerical scheme and an analysis of speed-up due to
parallelization on a graphics processing unit (GPU) is presented. It
is shown that speed-ups of ×30 are readily achievable.
---------------------------------------------------------
Title: Nonlinear Alfvén wave dynamics at a 2D magnetic null point:
ponderomotive force
Authors: Thurgood, J. O.; McLaughlin, J. A.
2013A&A...555A..86T Altcode: 2013arXiv1305.7073T
Context. In the linear, β = 0 MHD regime, the transient properties of
magnetohydrodynamic (MHD) waves in the vicinity of 2D null points are
well known. The waves are decoupled and accumulate at predictable parts
of the magnetic topology: fast waves accumulate at the null point;
whereas Alfvén waves cannot cross the separatricies. However, in
nonlinear MHD mode conversion can occur at regions of inhomogeneous
Alfvén speed, suggesting that the decoupled nature of waves may
not extend to the nonlinear regime. <BR /> Aims: We investigate the
behaviour of low-amplitude Alfvén waves about a 2D magnetic null point
in nonlinear, β = 0 MHD. <BR /> Methods: We numerically simulate
the introduction of low-amplitude Alfvén waves into the vicinity
of a magnetic null point using the nonlinear LARE2D code. <BR />
Results: Unlike in the linear regime, we find that the Alfvén wave
sustains cospatial daughter disturbances, manifest in the transverse and
longitudinal fluid velocity, owing to the action of nonlinear magnetic
pressure gradients (viz. the ponderomotive force). These disturbances
are dependent on the Alfvén wave and do not interact with the medium to
excite magnetoacoustic waves, although the transverse daughter becomes
focused at the null point. Additionally, an independently propagating
fast magnetoacoustic wave is generated during the early stages, which
transports some of the initial Alfvén wave energy towards the null
point. Subsequently, despite undergoing dispersion and phase-mixing
due to gradients in the Alfvén-speed profile (∇c<SUB>A</SUB> ≠
0) there is no further nonlinear generation of fast waves. <BR />
Conclusions: We find that Alfvén waves at 2D cold null points behave
largely as in the linear regime, however they sustain transverse and
longitudinal disturbances - effects absent in the linear regime -
due to nonlinear magnetic pressure gradients.
---------------------------------------------------------
Title: Hi-C and AIA observations of transverse magnetohydrodynamic
waves in active regions
Authors: Morton, R. J.; McLaughlin, J. A.
2013A&A...553L..10M Altcode: 2013arXiv1305.0140M
The recent launch of the High resolution Coronal imager (Hi-C)
provided a unique opportunity of studying the EUV corona with
unprecedented spatial resolution. We utilize these observations
to investigate the properties of low-frequency (50-200 s) active
region transverse waves, whose omnipresence had been suggested
previously. The five-fold improvement in spatial resolution over
SDO/AIA reveals coronal loops with widths 150-310 km and that these
loops support transverse waves with displacement amplitudes <50
km. However, the results suggest that wave activity in the coronal
loops is of low energy, with typical velocity amplitudes <3 km
s<SUP>-1</SUP>. An extended time-series of SDO data suggests that
low-energy wave behaviour is typical of the coronal structures both
before and after the Hi-C observations. <P />Appendix A and five
movies associated to Figs. A.2-A.6 are available in electronic form
at <A href="http://www.aanda.org">http://www.aanda.org</A>
---------------------------------------------------------
Title: Numerical Simulations of Magnetoacoustic-Gravity Waves in
the Solar Atmosphere
Authors: Murawski, K.; Srivastava, A. K.; McLaughlin, J. A.; Oliver, R.
2013SoPh..283..383M Altcode: 2012SoPh..tmp..328M; 2012arXiv1208.5837M
We investigate the excitation of magnetoacoustic-gravity waves
generated from localized pulses in the gas pressure as well as in the
vertical component of velocity. These pulses are initially launched
at the top of the solar photosphere, which is permeated by a weak
magnetic field. We investigate three different configurations of the
background magnetic field lines: horizontal, vertical, and oblique to
the gravitational force. We numerically model magnetoacoustic-gravity
waves by implementing a realistic (VAL-C) model of the solar
temperature. We solve the two-dimensional ideal magnetohydrodynamic
equations numerically with the use of the FLASH code to simulate the
dynamics of the lower solar atmosphere. The initial pulses result in
shocks at higher altitudes. Our numerical simulations reveal that a
small-amplitude initial pulse can produce magnetoacoustic-gravity
waves, which are later reflected from the transition region due
to the large-temperature gradient. The cavities in the lower solar
atmosphere are found to have the best conditions to act as a resonator
for various oscillations, including their trapping and leakage into
the higher atmosphere. Our numerical simulations successfully model
the excitation of such wave modes, their reflection and trapping,
as well as the associated plasma dynamics.
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Title: On the periodicity of oscillatory reconnection
Authors: McLaughlin, J. A.; Thurgood, J. O.; MacTaggart, D.
2012A&A...548A..98M Altcode: 2012arXiv1212.1000M
Context. Oscillatory reconnection is a time-dependent magnetic
reconnection mechanism that naturally produces periodic outputs
from aperiodic drivers. <BR /> Aims: This paper aims to quantify
and measure the periodic nature of oscillatory reconnection for the
first time. <BR /> Methods: We solve the compressible, resistive,
nonlinear magnetohydrodynamics (MHD) equations using 2.5D numerical
simulations. <BR /> Results: We identify two distinct periodic regimes:
the impulsive and stationary phases. In the impulsive phase, we find
the greater the amplitude of the initial velocity driver, the longer
the resultant current sheet and the earlier its formation. In the
stationary phase, we find that the oscillations are exponentially
decaying and for driving amplitudes 6.3-126.2 km s<SUP>-1</SUP>, we
measure stationary-phase periods in the range 56.3-78.9 s, i.e. these
are high frequency (0.01-0.02 Hz) oscillations. In both phases, we
find that the greater the amplitude of the initial velocity driver, the
shorter the resultant period, but note that different physical processes
and periods are associated with both phases. <BR /> Conclusions: We
conclude that the oscillatory reconnection mechanism behaves akin to
a damped harmonic oscillator.
---------------------------------------------------------
Title: Linear and nonlinear MHD mode coupling of the fast
magnetoacoustic wave about a 3D magnetic null point
Authors: Thurgood, J. O.; McLaughlin, J. A.
2012A&A...545A...9T Altcode: 2012arXiv1208.5885T
Context. Coronal magnetic null points have been implicated as possible
locations for localised heating events in 2D models. We investigate this
possibility about fully 3D null points. <BR /> Aims: We investigate
the nature of the fast magnetoacoustic wave about a fully 3D magnetic
null point, with a specific interest in its propagation, and we look
for evidence of MHD mode coupling and/or conversion to the Alfvén
mode. <BR /> Methods: A special fieldline and flux-based coordinate
system was constructed to permit the introduction of a pure fast
magnetoacoustic wave in the vicinity of proper and improper 3D null
points. We considered the ideal, β = 0, MHD equations, which are
solved using the LARE3D numerical code. The constituent modes of
the resulting wave were isolated and identified using the special
coordinate system. Numerical results were supported by analytical
work derived from perturbation theory and a linear implementation of
the WKB method. <BR /> Results: An initially pure fast wave is found
to be permanently decoupled from the Alfvén mode both linearly and
nonlinearly for both proper and improper 3D null points. The pure fast
mode also generates and sustains a nonlinear disturbance aligned along
the equilibrium magnetic field. The resulting pure fast magnetoacoustic
pulse has transient behaviour, which is found to be governed by the
(equilibrium) Alfvén-speed profile, and a refraction effect focuses
all the wave energy towards the null point. <BR /> Conclusions:
Thus, the main results from previous 2D work do indeed carry over
to the fully 3D magnetic null points and so we conclude that 3D null
points are locations for preferential heating in the corona by 3D fast
magnetoacoustic waves.
---------------------------------------------------------
Title: Generation of Quasi-periodic Waves and Flows in the Solar
Atmosphere by Oscillatory Reconnection
Authors: McLaughlin, J. A.; Verth, G.; Fedun, V.; Erdélyi, R.
2012ApJ...749...30M Altcode: 2012arXiv1203.6846M
We investigate the long-term evolution of an initially buoyant magnetic
flux tube emerging into a gravitationally stratified coronal hole
environment and report on the resulting oscillations and outflows. We
perform 2.5-dimensional nonlinear numerical simulations, generalizing
the models of McLaughlin et al. and Murray et al. We find that the
physical mechanism of oscillatory reconnection naturally generates
quasi-periodic vertical outflows, with a transverse/swaying aspect. The
vertical outflows consist of both a periodic aspect and evidence
of a positively directed flow. The speed of the vertical outflow
(20-60 km s<SUP>-1</SUP>) is comparable to those reported in the
observational literature. We also perform a parametric study varying
the magnetic strength of the buoyant flux tube and find a range of
associated periodicities: 1.75-3.5 minutes. Thus, the mechanism of
oscillatory reconnection may provide a physical explanation to some
of the high-speed, quasi-periodic, transverse outflows/jets recently
reported by a multitude of authors and instruments.
---------------------------------------------------------
Title: Determination of Sub-resolution Structure of a Jet by Solar
Magnetoseismology
Authors: Morton, R. J.; Verth, G.; McLaughlin, J. A.; Erdélyi, R.
2012ApJ...744....5M Altcode: 2011arXiv1109.4851M
A thin dark thread is observed in a UV/EUV solar jet in the 171 Å,
193 Å, and 211 Å, and partially in 304 Å. The dark thread appears
to originate in the chromosphere but its temperature does not appear
to lie within the passbands of the Atmospheric Imaging Assembly
onboard the Solar Dynamics Observatory. We therefore implement solar
magnetoseismology to estimate the plasma parameters of the dark
thread. A propagating kink (transverse) wave is observed to travel
along the dark thread. The wave is tracked over a range of ~7000 km
by placing multiple slits along the axis of the dark thread. The phase
speed and amplitude of the wave are estimated and magnetoseismological
theory is employed to determine the plasma parameters. We are able
to estimate the plasma temperature, density gradient, magnetic field
gradient, and sub-resolution expansion of the dark thread. The dark
thread is found to be cool, T <~ 3 × 10<SUP>4</SUP>, with both
strong density and magnetic field gradients. The expansion of the flux
tube along its length is ~300-400 km.
---------------------------------------------------------
Title: Review Article: MHD Wave Propagation Near Coronal Null Points
of Magnetic Fields
Authors: McLaughlin, J. A.; Hood, A. W.; de Moortel, I.
2011SSRv..158..205M Altcode: 2010SSRv..tmp..174M; 2010arXiv1004.5568M; 2010SSRv..tmp..157M
We present a comprehensive review of MHD wave behaviour in the
neighbourhood of coronal null points: locations where the magnetic
field, and hence the local Alfvén speed, is zero. The behaviour of
all three MHD wave modes, i.e. the Alfvén wave and the fast and slow
magnetoacoustic waves, has been investigated in the neighbourhood
of 2D, 2.5D and (to a certain extent) 3D magnetic null points, for
a variety of assumptions, configurations and geometries. In general,
it is found that the fast magnetoacoustic wave behaviour is dictated
by the Alfvén-speed profile. In a β=0 plasma, the fast wave is
focused towards the null point by a refraction effect and all the
wave energy, and thus current density, accumulates close to the null
point. Thus, null points will be locations for preferential heating
by fast waves. Independently, the Alfvén wave is found to propagate
along magnetic fieldlines and is confined to the fieldlines it is
generated on. As the wave approaches the null point, it spreads out due
to the diverging fieldlines. Eventually, the Alfvén wave accumulates
along the separatrices (in 2D) or along the spine or fan-plane (in
3D). Hence, Alfvén wave energy will be preferentially dissipated at
these locations. It is clear that the magnetic field plays a fundamental
role in the propagation and properties of MHD waves in the neighbourhood
of coronal null points. This topic is a fundamental plasma process and
results so far have also lead to critical insights into reconnection,
mode-coupling, quasi-periodic pulsations and phase-mixing.
---------------------------------------------------------
Title: Phase mixing of nonlinear visco-resistive Alfvén waves
Authors: McLaughlin, J. A.; de Moortel, I.; Hood, A. W.
2011A&A...527A.149M Altcode: 2011arXiv1101.5945M
<BR /> Aims: We investigate the behaviour of nonlinear, nonideal Alfvén
wave propagation within an inhomogeneous magnetic environment. <BR />
Methods: The governing MHD equations are solved in 1D and 2D using
both analytical techniques and numerical simulations. <BR /> Results:
We find clear evidence for the ponderomotive effect and visco-resistive
heating. The ponderomotive effect generates a longitudinal component
to the transverse Alfvén wave, with a frequency twice that of the
driving frequency. Analytical work shows the addition of resistive
heating. This leads to a substantial increase in the local temperature
and thus gas pressure of the plasma, resulting in material being pushed
along the magnetic field. In 2D, our system exhibits phase mixing and
we observe an evolution in the location of the maximum heating, i.e. we
find a drifting of the heating layer. <BR /> Conclusions: Considering
Alfvén wave propagation in 2D with an inhomogeneous density gradient,
we find that the equilibrium density profile is significantly modified
by both the flow of density due to visco-resistive heating and the
nonlinear response to the localised heating through phase mixing.
---------------------------------------------------------
Title: A finite-difference algorithm for full waveform teleseismic
tomography
Authors: Roecker, S.; Baker, B.; McLaughlin, J.
2010GeoJI.181.1017R Altcode:
We adapt a 2-D spectral domain finite difference waveform tomography
algorithm previously used in active source seismological imaging to
the case of a plane wave propagating through a 2.5-D viscoelastic
medium in order to recover P and S wave speed variations from body
waves recorded at teleseismic distances. A transferable efficacy that
permits recovery of arbitrarily heterogenous models on moderately
sized computers provides the primary motivation for choosing this
algorithm. Synthetic waveforms can be generated either by specifying
an analytic solution for a background plane wave in a 1-D model and
solving for the source distribution that would produce it, or by solving
for a scattered field excited by a plane wave source and then adding
the background wavefield to it. Because the former approach typically
involves a concentration of sources at the free surface, the latter
tends to be more stable numerically. We adapt a gradient approach to
solve the inverse problem to maintain tractability; calculating the
gradient does not require much more computational effort than does
the forward problem. The waveform tomography algorithm can be applied
in a straightforward way to perform receiver function migration and
traveltime inversion.
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Title: Impulsively generated oscillations in a 3D coronal loop
Authors: Pascoe, D. J.; de Moortel, I.; McLaughlin, J. A.
2009A&A...505..319P Altcode:
Aims: The effect of changing the attack angle for the interaction of
a fast MHD wave with a 3D coronal loop is studied, to investigate
to what extent the properties of the excited transverse kink mode
oscillations of the loop depend on this angle. <BR />Methods: 3D
numerical simulations are performed of the interaction of a fast
MHD wave, generated by a pressure pulse, with a 3D coronal loop. The
loop itself is modelled as a density enhancement (with a finite plasma
beta) within a magnetic arcade. The initial pressure pulse has a width
comparable to the loop diameter and is situated outside of the loop,
at the same height as the loop apex. This height is kept fixed but
the (horizontal) angle between the pressure pulse and the loop is
varied. <BR />Results: We find that the global, transverse kink mode is
efficiently excited for a range of attack angles and qualitatively in
agreement with theoretical expectations. The period and damping time are
found to be independent of the attack angle. For larger values of the
attack angle, the global (longitudinal) slow wave is excited, whereas
for intermediate values the second harmonic kink mode is also present.
---------------------------------------------------------
Title: Nonlinear fast magnetoacoustic wave propagation in the
neighbourhood of a 2D magnetic X-point: oscillatory reconnection
Authors: McLaughlin, J. A.; De Moortel, I.; Hood, A. W.; Brady, C. S.
2009A&A...493..227M Altcode: 2009arXiv0901.1781M
Context: This paper extends the models of Craig & McClymont
(1991, ApJ, 371, L41) and McLaughlin & Hood (2004, A&A,
420, 1129) to include finite β and nonlinear effects. <BR />Aims:
We investigate the nature of nonlinear fast magnetoacoustic waves
about a 2D magnetic X-point. <BR />Methods: We solve the compressible
and resistive MHD equations using a Lagrangian remap, shock capturing
code (Arber et al. 2001, J. Comp. Phys., 171, 151) and consider an
initial condition in {v}×{B} \cdot {hat{z}} (a natural variable of
the system). <BR />Results: We observe the formation of both fast and
slow oblique magnetic shocks. The nonlinear wave deforms the X-point
into a “cusp-like” point which in turn collapses to a current
sheet. The system then evolves through a series of horizontal and
vertical current sheets, with associated changes in connectivity,
i.e. the system exhibits oscillatory reconnection. Our final state is
non-potential (but in force balance) due to asymmetric heating from
the shocks. Larger amplitudes in our initial condition correspond to
larger values of the final current density left in the system. <BR
/>Conclusions: The inclusion of nonlinear terms introduces several
new features to the system that were absent from the linear regime. <P
/>A movie is available in electronic form at http://www.aanda.org
---------------------------------------------------------
Title: Influence of a dense photosphere-like layer on vertical
oscillations of a curved coronal slab
Authors: Gruszecki, M.; Murawski, K.; McLaughlin, J. A.
2008A&A...489..413G Altcode:
Aims: We consider a model of a two-dimensional curved solar coronal slab
and explore the excitation and attenuation of fast magnetoacoustic
vertical oscillations. We include a dense photosphere-like layer
into the physical system. <BR />Methods: The time-dependent, ideal
magnetohydrodynamic equations are solved numerically to determine
the spatial and temporal signatures of the impulsively excited
oscillations. <BR />Results: The numerical results reveal that
the inclusion of the dense photosphere-like layer has a significant
influence on the wave period (P) and attenuation time (τ ). The wave
characteristics exhibit a stronger dependence on the mass density
contrast between the loop and the photosphere than on the width of the
transition layer, according to the parametric studies performed here. We
find that P decreases and τ /P grows with the mass density contrast
between the photosphere-like layer and solar corona, d_ph. At the limit
of d_ph→ ∞ , P and τ /P attain their values which correspond to
the case when the photosphere-like layer is removed from the system
and its action is mimicked by implementation of line-tying boundary
conditions at the bottom boundary. <BR />Conclusions: The inclusion
of a dense photosphere-like layer results in more efficient excitation
and attenuation of vertical waves oscillation, compared with the case
of line-tying boundary conditions. The enhancement of the attenuation
rate arises from energy leakage through the photosphere-like layer.
---------------------------------------------------------
Title: 3D MHD Coronal Oscillations about a Magnetic Null Point:
Application of WKB Theory
Authors: McLaughlin, J. A.; Ferguson, J. S. L.; Hood, A. W.
2008SoPh..251..563M Altcode: 2007arXiv0712.1731M; 2008SoPh..tmp....8M
This paper is a demonstration of how the WKB approximation can
be used to help solve the linearised 3D MHD equations. Using
Charpit's method and a Runge - Kutta numerical scheme, we have
demonstrated this technique for a potential 3D magnetic null point,
B=[x,εy,−(ε+1)z]. Under our cold-plasma assumption, we have
considered two types of wave propagation: fast magnetoacoustic and
Alfvén waves. We find that the fast magnetoacoustic wave experiences
refraction towards the magnetic null point and that the effect of this
refraction depends upon the Alfvén speed profile. The wave and thus the
wave energy accumulate at the null point. We have found that current
buildup is exponential and the exponent is dependent upon ε. Thus,
for the fast wave there is preferential heating at the null point. For
the Alfvén wave, we find that the wave propagates along the field
lines. For an Alfvén wave generated along the fan plane, the wave
accumulates along the spine. For an Alfvén wave generated across the
spine, the value of ε determines where the wave accumulation will
occur: fan plane (ε=1), along the x-axis (0<ε<1) or along the
y-axis (ε>1). We have shown analytically that currents build up
exponentially, leading to preferential heating in these areas. The work
described here highlights the importance of understanding the magnetic
topology of the coronal magnetic field for the location of wave heating.
---------------------------------------------------------
Title: Three-dimensional Magnetohydrodynamic Wave Behavior in Active
Regions: Individual Loop Density Structure
Authors: McLaughlin, J. A.; Ofman, L.
2008ApJ...682.1338M Altcode:
We present the numerical results from a three-dimensional (3D) nonlinear
MHD simulation of wave activity in an idealized active region in
which individual, realistic loop density structure is included. The
active region is modeled by an initially force-free, dipole magnetic
configuration with gravitationally stratified density and contains a
loop with a higher density than its surroundings. This study represents
an extension to the model of Ofman & Thompson. As found in their
work, we see that fast wave propagation is distorted by the Alfvén
speed profile and that the wave propagation generates field line
oscillations, which are rapidly damped. We find that the addition of
a high-density loop significantly changes the behavior inside that
loop, specifically in that the loop can support trapped waves. We
also find that the impact of the fast wave impulsively excites both
horizontal and vertical loop oscillations. From a parametric study
of the oscillations, we find that the amplitude of the oscillations
decreases with increasing density contrast, whereas the period and
damping time increase. This is one of the key results presented here:
that individual loop density structure can influence the damping rate,
and specifically that the damping time increases with increasing density
contrast. All these results were compared with an additional study
performed on a straight coronal loop with similar parameters. Through
comparison with the straight loop, we find that the damping mechanism
in our curved loop is wave leakage due to curvature. The work performed
here highlights the importance of including individual loop density
structure in the modeling of active regions and illustrates the need
for obtaining accurate density measurements for coronal seismology.
---------------------------------------------------------
Title: 3d Simulations Of Excitation And Damping Of Waves In A Dipole
Active Region
Authors: Selwa, Malgorzata; Ofman, L.; McLaughlin, J.
2007AAS...210.9114S Altcode: 2007BAAS...39R.206S
We present numerical results of three dimensional MHD model of an
idealized active region field. The active region is initialized
as a force-free dipole magnetic configuration with gravitationally
stratified density and contains a loop with a higher density than
its surroundings. This study represents an extension to the model of
McLaughlin & Ofman (2007). We examine the impact of a different
density profiles of the loop on excitation and damping of kink waves by
introducing a velocity or pressure pulse which models the impact of a
flare on surrounding fields. We study the resulting loop oscillations
and compare our results with TRACE observations.
---------------------------------------------------------
Title: 3D MHD Model of Waves in an Active Region
Authors: Ofman, L.; McLaughlin, J.
2006AGUFMSH33B0416O Altcode:
Wave activity associated with flares and CME's have been observed with
SOHO, TRACE, and other satellites. The propagation and dissipation of
the waves provide information on the coronal magnetic structures. In
particular, MHD waves were observed in coronal active region AR8270
following a flare with TRACE on July 14, 1998. In this study, three
dimensional MHD model of the active region field was constructed using
National Solar Observatory (NSO) Kitt Peak magnetogram and potential
extrapolation of the magnetic field, together with gravitationally
stratified density as the initial state. The model was evolved to steady
state, and a velocity pulse with amplitude of ~100 km/sec was launched
into the active region from below to mimic the observed effect of the
flare. It was found that the global oscillations in the model active
region are in good qualitative agreement with observations. The main
difference between the observations and the model is in the oscillation
of several individual loops that damp on longer time scale, compared
to the corresponding magnetic field line oscillation damping in the
model. We investigate the effects of global active region magnetic
structure, as well as local loop structure on the trapping and damping
of waves in the active region.
---------------------------------------------------------
Title: 3D MHD Wave Behavior in Active Regions: Trapped Modes
Authors: McLaughlin, J. A.; Ofman, L.
2006AGUFMSH33B0413M Altcode:
We present the numerical results of a fast magnetoacoustic wave
propagating within an idealized active region. The active region is
modeled by an initially force-free, dipole magnetic configuration with
gravitationally stratified density and contains a loop with a higher
density than its surroundings. This study represents an extension to
the model of Ofman &Thompson (2002). As found in their work, we see
that fast wave propagation is distorted by the Alfvén speed profile
and that the wave propagation generates fieldline oscillations and
these oscillations are rapidly damped. Inside the high density loop,
we find that the amplitude of these oscillations decreases as the
density contrast, ξ, increases. We also find that the high density
loop undergoes both vertical and horizontal oscillations. We calculate
how the rate of wave damping in our loop varies with ξ and find a
local minimum at about ξ=2.5, and we argue that this is evidence of
wave trapping. Thus, this work illustrates the importance of obtaining
accurate loop density measurements for coronal seismology.
---------------------------------------------------------
Title: MHD mode coupling in the neighbourhood of a 2D null point
Authors: McLaughlin, J. A.; Hood, A. W.
2006A&A...459..641M Altcode: 2007arXiv0712.2402M
Context: .At this time there does not exist a robust set of rules
connecting low and high β waves across the β ≈ 1 layer. The work
here contributes specifically to what happens when a low β fast
wave crosses the β ≈ 1 layer and transforms into high β fast and
slow waves.<BR /> Aims: .The nature of fast and slow magnetoacoustic
waves is investigated in a finite β plasma in the neighbourhood of a
two-dimensional null point.<BR /> Methods: .The linearised equations are
solved in both polar and cartesian forms with a two-step Lax-Wendroff
numerical scheme. Analytical work (e.g. small β expansion and WKB
approximation) also complement the work.<BR /> Results: .It is found
that when a finite gas pressure is included in magnetic equilibrium
containing an X-type null point, a fast wave is attracted towards
the null by a refraction effect and that a slow wave is generated
as the wave crosses the β ≈ 1 layer. Current accumulation occurs
close to the null and along nearby separatrices. The fast wave
can now pass through the origin due to the non-zero sound speed,
an effect not previously seen in related papers but clear seen for
larger values of β. Some of the energy can now leave the region of
the null point and there is again generation of a slow wave component
(we find that the fraction of the incident wave converted to a slow
wave is proportional to β). We conclude that there are two competing
phenomena; the refraction effect (due to the variable Alfvén speed)
and the contribution from the non-zero sound speed.<BR /> Conclusions:
.These experiments illustrate the importance of the magnetic topology
and of the location of the β ≈ 1 layer in the system.
---------------------------------------------------------
Title: Three-Dimensional MHD Models of Waves in Active Regions:
Application to Coronal Seismology
Authors: McLaughlin, J. A.; Ofman, L.
2006ESASP.617E.102M Altcode: 2006soho...17E.102M
We present results from three-dimensional MHD simulations of the
behaviour of MHD waves in 3D models of coronal active regions and
loops. The models of the active regions are constructed by using a
dipole magnetic field and gravitationally stratified coronal density
structure. We compare the main features of the model with those
seen recently by the SOHO and TRACE satellites and investigate the
application of the results to coronal seismology. We discuss the
possible applications of STEREO data to the improvement of our model.
---------------------------------------------------------
Title: Waves In Active Regions: Comparing Observations And 3D
MHD Models
Authors: Ofman, Leon; McLaughlin, J.
2006SPD....37.1802O Altcode: 2006BAAS...38..246O
Recent TRACE observations of active regions in EUV shows waveactivity
in coronal active regions following impulsive events.Motivated by
these observations we construct 3D MHD models of theactive regions
using photospheric magnetic field as boundarycondition from SOHO
MDI or Kitt Peak data, and nonuniform densitystructure to model
individual loops. We introduce several forms ofvelocity and density
pulses to model the effects of impulsiveevents, such as flares,
and follow the evolution of the modelactive region. We find good
agreement between the observedevolution of active regions, and the 3D
MHD models. Thus, wedemonstrate that the 3D MHD models can be used
for coronalseismology. In the near future STEREO data may provide
improvedinput for these models.
---------------------------------------------------------
Title: Magnetohydrodynamics wave propagation in the neighbourhood
of two dipoles
Authors: McLaughlin, J. A.; Hood, A. W.
2006A&A...452..603M Altcode: 2007arXiv0712.1784M
Context: .This paper is the third in a series of investigations by the
authors.<BR /> Aims: .The nature of fast magnetoacoustic and Alfvén
waves is investigated in a 2D β=0 plasma in the neighbourhood of two
dipoles.<BR /> Methods: .We use both numerical simulations (two-step
Lax-Wendroff scheme) and analytical techniques (WKB approximation).<BR
/> Results: .It is found that the propagation of the linear fast wave
is dictated by the Alfvén speed profile and that close to the null,
the wave is attracted to the neutral point. However, it is also found
that in this magnetic configuration some of the wave can escape the
refraction effect; this had not been seen in previous investigations by
the authors. The wave split occurs near the regions of very high Alfvén
speed (found near the loci of the two dipoles). Also, for the set-up
investigated it was found that 40% of the wave energy accumulates at
the null. Ohmic dissipation will then extract the wave energy at this
point. The Alfvén wave behaves in a different manner in that part of
the wave accumulates along the separatrices and part escapes. Hence, the
current density will accumulate at this part of the topology and this
is where wave heating will occur.<BR /> Conclusions: .The phenomenon
of wave accumulation at a specific place is a feature of both wave
types, as is the result that a fraction of the wave can now escape
the numerical box when propagating in this magnetic configuration.
---------------------------------------------------------
Title: 3d Mhd Wave Behavior In Active Regions: Modeling Techniques
Authors: McLaughlin, James A.; Ofman, L.
2006SPD....37.0116M Altcode: 2006BAAS...38..218M
We have performed simulations of three-dimensional MHD wave propagation
in models of coronal active regions. Here, we present descriptions of
the methodology and techniques that are used in the construction of such
simulations. These include:1) The MHD equations solved and the velocity
perturbations used to simulate, for example, incoming EIT waves.2)
The construction of the active region model using extrapolations of the
observed photospheric magnetic field and gravitational stratification of
the coronal density structure.3) The inclusion of the density structure
of individual, realistic coronal loops using a new technique.We also
discuss the application of the model to coronal seismology and the
possibility of using STEREO data to the improvement of the simulations.
---------------------------------------------------------
Title: 3D MHD models of waves in active regions: application to
coronal seismology
Authors: McLaughlin, J. A.; Ofman, L.
2006AGUSMSH52A..06M Altcode:
We present results from three-dimensional MHD simulations of the
behavior of MHD waves in realistic models of coronal active regions. The
models of the active regions are constructed by using the observed
photospheric magnetic field and gravitationally stratified coronal
density structure with individual loops. We compare the main features
of the model with those seen recently by the SOHO and TRACE satellites,
and investigate the application of the results to coronal seismology. We
discuss the possible application of STEREO data to the improvement of
our model.
---------------------------------------------------------
Title: MHD wave propagation in the neighbourhood of two null points
Authors: McLaughlin, J. A.; Hood, A. W.
2005A&A...435..313M Altcode: 2007arXiv0712.1809M
The nature of fast magnetoacoustic and Alfvén waves is investigated
in a zero β plasma in the neighbourhood of a pair of two-dimensional
null points. This gives an indication of wave propagation in the low
β solar corona, for a more complicated magnetic configuration than
that looked at by McLaughlin & Hood (2004, A&A, 420, 1129). It
is found that the fast wave is attracted to the null points and that
the front of the wave slows down as it approaches the null point
pair. Here, the wave splits and part of the wave accumulates at one
null and the rest at the other. Current density will then accumulate
at these points and ohmic dissipation will then extract the energy in
the wave at these points. This suggests locations where wave heating
will occur in the corona. The Alfvén wave behaves in a different
manner in that the wave accumulates along the separatrices. Hence,
the current density will accumulate at this part of the topology and
this is where wave heating will occur. However, the phenomenon of
wave accumulation at a specific place is a feature of both wave types,
and illustrates the importance of studying the topology of the corona
when considering MHD wave propagation.
---------------------------------------------------------
Title: GRB 050525a: SARA observations.
Authors: Homewood, A.; Hartmann, D. H.; Garimella, K.; Henson, G.;
McLaughlin, J.; Brimeyer, A.
2005GCN..3491....1H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Preferential Heating in the Neighbourhood of a Two-Dimensional
Null Point
Authors: McLaughlin, J. A.; Hood, A. W.
2004ESASP.575...74M Altcode: 2004soho...15...74M
No abstract at ADS
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Title: MHD wave propagation in the neighbourhood of a two-dimensional
null point
Authors: McLaughlin, J. A.; Hood, A. W.
2004A&A...420.1129M Altcode: 2007arXiv0712.1792M
The nature of fast magnetoacoustic and Alfvén waves is investigated
in a zero β plasma. This gives an indication of wave propagation in
the low β solar corona. It is found that for a two-dimensional null
point, the fast wave is attracted to that point and the front of the
wave slows down as it approaches the null point, causing the current
density to accumulate there and rise rapidly. Ohmic dissipation will
extract the energy in the wave at this point. This illustrates that
null points play an important role in the rapid dissipation of fast
magnetoacoustic waves and suggests the location where wave heating will
occur in the corona. The Alfvén wave behaves in a different manner in
that the wave energy is dissipated along the separatrices. For Alfvén
waves that are decoupled from fast waves, the value of the plasma β
is unimportant. However, the phenomenon of dissipating the majority
of the wave energy at a specific place is a feature of both wave types.
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Title: MHD Waves in the Neighbourhood of a 2D X-Type Neutral Point
Authors: McLaughlin, J. A.; Hood, A. W.
2004ESASP.547..537M Altcode: 2004soho...13..537M
A linear, fast magnetoacoustic wave is generated at a boundary and
travels towards an magnetic X-type neutral point. Due to refraction,
the wave wraps itself around the null point, causing a large current
to accumulate there. Simulations show that the current build up is
exponential in time. The numerical simulations are in good agreement
with analytic work based on a WKB solution obtained by the method
of characteristics.
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Title: The Use of Zylon Fibers in ULDB Balloons
Authors: Zimmerman, M.; Seely, L.; McLaughlin, J.
2002cosp...34E2817Z Altcode: 2002cosp.meetE2817Z
Early in the development of the ULDB balloon, Zylon (PBO) was
selected as the tendon material due to its favorable stress-strain
properties. It is a next generation super fiber whose strength and
modulus are almost double those of the p-Aramid fibers. In addition
there are two versions of the Zylon, As Spun (AS) and High Modulus
(HM). Data will be presented on why the HM was chosen. Early in the
development process, it was learned that this material exhibited an
unusual sensitivity to degradation by ambient light. This is in addition
to the expected sensitivity to UV radiation (Ultraviolet). The fiber
manufacturer reported all of these properties in their literature. Due
to the operating environment of the ULDB (Ultra Long Duration Balloon)
it is necessary to protect the tendons from both visible and UV
radiation. Methods to protect the tendons will be discussed. In
addition, information on the long term exposure of the braided tendon
over a thirty-six month period in a controlled manufacturing plant
will be provided.
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Title: Periodic Comet Swift-Tuttle (1992t)
Authors: Jones, B.; Pina, R. K.; Milone, E. F.; Sarmecanic, J. R.;
Puetter, R. C.; McLaughlin, J.; Gehrz, R. D.; Lawrence, G.; Flugaur,
K.; Woodward, C. E.
1992IAUC.5654....2J Altcode:
B. Jones and R. K. Pina, University of California at San Diego; and
E. F. Milone, Rothney Astrophysical Observatory, University of Calgary,
report that 11.7-micron images (0".83/pixel) of P/Swift- Tuttle were
obtained on Nov. 7.1 and 8.1 UT by Pina, J. R. Sarmecanic, and Milone
(field-of-view of 30" x 17") and on Nov. 12.1 and 13.1 by R. C. Puetter
and J. McLaughlin (19" x 24"), using the UCSD 10-micron array camera
at the Mt. Lemmon Infrared Observatory. The comet showed a decrease
in flux of 28 percent between the two dates, going from 37.7 to 27.3
Jy in a 5".8 beam centered on the nucleus. R. D. Gehrz, G. Lawrence,
and K. Flugaur, University of Minnesota; and C. E. Woodward, University
of Wyoming, report thermal infrared measurements of P/Swift-Tuttle on
Nov. 12.0 UT using a multifilter GaGe bolometer with a 9" diaphragm
on the 0.76-m telescope of O'Brien Observatory. The chopper throw
placed the reference beams 45" north and south of the coma center. The
infrared broadband magnitudes are K [6.53 (3-sigma upper limit), L =
5.9 +/- 0.3, M = 3.0 +/- 0.3, N (7-14 microns) = -0.2 +/- 0.1, Q (18-22
microns) [-2.0 (3-sigma upper limit). Additional photometry through the
narrow-band IRTF silicate filter set gave magnitudes of [7.8 microns]
= 0.7 +/- 0.3, [8.7 microns] = -0.3 +/- 0.1, [9.8 microns] = -0.7
+/- 0.15, [10.3 microns] = -0.64 +/- 0.3, [11.6 microns] = -1.4 +/-
0.3, and [12.5 microns] = -1.1 +/- 0.1. The data are consistent with
continuum emission from a 367-K blackbody. There is no evidence for
a strong 10-micron silicate emission feature.
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Title: An example of the Vilkovisky-de Witt effective action in
one-loop quantum gravity.
Authors: Allen, B.; McLaughlin, J.; Ottewill, A. C.
1992mgm..conf..545A Altcode:
No abstract at ADS
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Title: Renormalised Energy Density on the Horizon of a Kerr Black Hole
Authors: Jensen, B.; McLaughlin, J.; Ottewill, A.
1989grg..conf..697J Altcode:
No abstract at ADS