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Related papers: Relationship between non-thermal electron energy s…

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Numerical models of collisionless shocks robustly predict an electron distribution comprised of both thermal and non-thermal electrons. Here, we explore in detail the effect of thermal electrons on the emergent synchrotron emission from…

High Energy Astrophysical Phenomena · Physics 2021-12-22 Ben Margalit , Eliot Quataert

We study the energetics of nonthermal electrons produced in small acceleration episodes in the solar corona. We carried out an extensive survey spanning 2004--2015 and shortlisted 6 impulsive electron events detected at 1 AU that was not…

Solar and Stellar Astrophysics · Physics 2017-11-20 Tomin James , Prasad Subramanian , Eduard P Kontar

The GOES M2-class solar flare, SOL2010-06-12T00:57, was modest in many respects yet exhibited remarkable acceleration of energetic particles. The flare produced an ~50 s impulsive burst of hard X- and \gamma-ray emission up to at least 400…

High Energy Astrophysical Phenomena · Physics 2017-02-22 Fermi GBM Collaboration , Fermi LAT Collaboration , B. R. Dennis , R. A. Schwartz , A. K. Tolbert

We investigate the signature of the photospheric albedo contribution in solar flare hard X-ray spectra, the effect of low energy cutoffs in electron spectra, and the directivity of hard X-ray emission. Using Ramaty High Energy Solar…

Astrophysics · Physics 2008-11-26 J. Kasparova , E. P. Kontar , J. C. Brown

The explanation of the coronal heating problem potentially lies in the existence of nanoflares, numerous small-scale heating events occuring across the whole solar disk. In this paper, we present the first imaging spectroscopy X-ray…

Sunquakes are enhanced seismic waves excited in some energetic solar flares. Up to now, their origin has still been controversial. In this Letter, we select and study 20 strong flares in Solar Cycle 24, whose impulse phase is fully captured…

Solar and Stellar Astrophysics · Physics 2023-02-01 H. Wu , Y. Dai , M. D. Ding

We investigated the frequency distributions of flares with and without coronal mass ejections (CMEs) as a function of flare parameters (peak flux, fluence, and duration of soft X-ray flares). We used CMEs observed by the Large Angle and…

Astrophysics · Physics 2011-02-11 S. Yashiro , S. Akiyama , N. Gopalswamy , R. A. Howard

X-ray observations provide important and valuable insights into the acceleration and propagation of nonthermal electrons during solar flares. Improved X-ray spectral analysis requires a deeper understanding of the dynamics of energetic…

Solar and Stellar Astrophysics · Physics 2024-10-15 Yingjie Luo , Eduard P. Kontar , Debesh Bhattacharjee

Here we present the results of the study of the north-south (N-S) distribution and asymmetry of GOES soft X-ray (SXR) flares during solar cycle 24. The period of study includes ascending, maximum and descending phases of the cycle. During…

Solar and Stellar Astrophysics · Physics 2020-07-15 Anita Joshi , Ramesh Chandra

Solar and stellar flares are powerful events which produce intense radiation across the electromagnetic spectrum. Multiwavelength observations are highly important for understanding the nature of flares, because different flare-related…

Solar and Stellar Astrophysics · Physics 2021-05-12 Alexey A. Kuznetsov , Dmitrii Y. Kolotkov

We studied the soft X-ray data of solar flares and found that the distribution functions of flare fluence are successfully modeled by tapered power law or gamma function distributions whose power exponent is slightly smaller than 2,…

Solar and Stellar Astrophysics · Physics 2022-12-07 Takashi Sakurai

Some 15% of solar flares having a soft X-ray flux above GOES class C5 are reported to lack coherent radio emission in the 100 - 4000 MHz range (type I - V and decimetric emissions). A detailed study of 29 such events reveals that 22 (76%)…

Astrophysics · Physics 2009-11-13 Arnold O. Benz , Roman Brajsa , Jasmina Magdalenic

During a solar flare, the fluxes in various lines and continua of the solar spectrum increase, leading to enhanced ionization of the illuminated part of the Earth's ionosphere and an increase in the total electron content (TEC). It has been…

Space Physics · Physics 2025-09-01 S. Z. Bekker , R. O. Milligan , I. A. Ryakhovsky

Superflares on solar-type stars has been a rapidly developing field ever since the launch of $\it Kepler$. Over the years, there have been several studies investigating the statistics of these explosive events. In this study, we present a…

Solar and Stellar Astrophysics · Physics 2020-04-22 Lauren Doyle , Gavin Ramsay , J. Gerard Doyle

Recent observations and simulations indicate that solar flares undergo extremely complex three-dimensional (3D) evolution, making 3D particle transport models essential for understanding electron acceleration and interpreting flare…

Solar and Stellar Astrophysics · Physics 2025-08-19 Xiaocan Li , Chengcai Shen , Xiaoyan Xie , Fan Guo , Bin Chen , Ivan Oparin , Yuqian Wei , Sijie Yu , Jeongbhin Seo

We conduct two-dimensional particle-in-cell simulations to investigate the scattering of electron heat flux by self-generated oblique electromagnetic waves. The heat flux is modeled as a bi-kappa distribution with a T_parallel > T_perp…

Solar and Stellar Astrophysics · Physics 2023-07-12 Hanqing Ma , James F. Drake , Marc Swisdak

RHESSI observations of elementary flare bursts are presented. These solar flare elements are distinct emission peaks of a duration of some tens of seconds present in the hard X-ray light curves. They are characterized by consistent…

Astrophysics · Physics 2007-05-23 Paolo C. Grigis , Arnold O. Benz

The mid-infrared (mid-IR) range has been mostly unexplored for the investigation of solar flares. It is only recently that new mid-IR flare observations have begun opening a new window into the response and evolution of the solar…

With the elementary energy release events introduced in a previous paper (Liu & Fletcher 2009) we model the chromospheric evaporation in flaring loops. The thick-target hard X-ray (HXR) emission produced by electrons escaping from the…

Solar and Stellar Astrophysics · Physics 2014-11-20 Siming Liu , Feiran Han , Lyndsay Fletcher

Particle acceleration in solar flares remains an outstanding problem in solar physics. It is yet unclear which of the acceleration mechanisms dominates and how exactly is the excessive magnetic energy transferred to the nonthermal and other…

Solar and Stellar Astrophysics · Physics 2019-09-25 Alexander T. Altyntsev , Nataliia S. Meshalkina , Alexandra L. Lysenko , Gregory D. Fleishman
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