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We develop a model of particle energization and emission from strongly turbulent black-hole coronae. Our local model is based on a set of 2D radiative particle-in-cell simulations with an electron-ion plasma composition, injection and…

High Energy Astrophysical Phenomena · Physics 2026-04-07 Daniel Groselj , Alexander Philippov , Andrei M. Beloborodov , Richard Mushotzky

Imaging spectroscopy in X-rays with RHESSI provide the possibility to investigate the spatial evolution of the X-ray emitting electron distribution and therefore to study the transport effects on energetic electrons during solar flares. We…

Solar and Stellar Astrophysics · Physics 2018-02-07 S. Musset , E. P. Kontar , N. Vilmer

Finite thermal velocity modifications to electron slowing-down rates may be important for the deduction of solar flare total electron energy. Here we treat both slowing-down and velocity diffusion of electrons in the corona at flare…

Astrophysics · Physics 2009-11-11 Ross K. Galloway , Alexander L. MacKinnon , Eduard P. Kontar , Per Helander

This paper reports on the re-analysis of solar flares in which the hard X-rays (HXRs) come predominantly from the corona rather than from the more usual chromospheric footpoints. All of the 26 previously analyzed event time intervals, over…

Solar and Stellar Astrophysics · Physics 2018-11-07 Brian R. Dennis , Miguel A. Duval-Poo , Michele Piana , Andrew R. Inglis , A. Gordon Emslie , Jingnan Guo , Yan Xu

X-ray observations are a powerful diagnostic tool for transport, acceleration, and heating of electrons in solar flares. Height and size measurements of X-ray footpoints sources can be used to determine the chromospheric density and…

Solar and Stellar Astrophysics · Physics 2015-06-04 Marina Battaglia , Eduard P. Kontar , Lyndsay Fletcher , Alec L. MacKinnon

Solar flare electron acceleration is an efficient process, but its properties (mechanism, location) are not well constrained. Via hard X-ray (HXR) emission, we routinely observe energetic electrons at the Sun, and sometimes we detect…

Solar and Stellar Astrophysics · Physics 2023-10-09 Ross Pallister , Natasha L. S. Jeffrey

Investigate the spatial and spectral evolution of hard X-ray (HXR) emission from flare accelerated electron beams subject to collisional transport and wave-particle interactions in the solar atmosphere. We numerically follow the propagation…

Solar and Stellar Astrophysics · Physics 2015-05-27 I. G. Hannah , E. P. Kontar

This paper studies acceleration processes of background thermal electrons in X-ray binary jets via turbulent stochastic interactions and shock collisions. By considering turbulent magnetized jets mixed with fluctuation magnetic fields and…

High Energy Astrophysical Phenomena · Physics 2017-11-29 Jian-Fu Zhang , Zhi-Ren Li , Fu-Yuan Xiang , Ju-Fu Lu

Nonthermal sources located above bright flare arcades, referred to as the "above-the-loop-top" sources, have been often suggested as the primary electron acceleration site in major solar flares. The X8.2 limb flare on 2017 September 10…

Solar and Stellar Astrophysics · Physics 2021-03-03 Bin Chen , Marina Battaglia , Säm Krucker , Katharine K. Reeves , Lindsay Glesener

The thick-target model predicts that in flare foot points, we should observe lowering of HXR sources' altitude with increasing energy. The foot point of HXR sources result from the direct interaction of non-thermal electron beams with…

Solar and Stellar Astrophysics · Physics 2022-03-14 T. Mrozek , R. Falewicz , S. Kolomanski , M. Litwicka

This study explores the impact of a turbulent scattering mechanism, akin to those influencing solar and galactic cosmic rays propagating in the interplanetary medium, on the population of suprathermal electrons in the solar wind. We employ…

A number of double coronal X-ray sources have been observed during solar flares by RHESSI, where the two sources reside at different sides of the inferred reconnection site. However, where and how are these X-ray-emitting electrons…

Solar and Stellar Astrophysics · Physics 2022-07-20 Xiangliang Kong , Jing Ye , Bin Chen , Fan Guo , Chengcai Shen , Xiaocan Li , Sijie Yu , Yao Chen , Joe Giacalone

The aim of this paper is to investigate the spatial structure of the impulsive phase hard X-ray emission from solar flares. This work is motivated by the YOHKOH and the forthcoming HESSI observations. Summarizing past results, it is shown…

Astrophysics · Physics 2009-10-31 Vahe Petrosian , Timothy Q. Donaghy

We present detailed 3D modeling of a dense, coronal thick target X-ray flare using the GX Simulator tool, photospheric magnetic measurements, and microwave imaging and spectroscopy data. The developed model offers a remarkable agreement…

Solar and Stellar Astrophysics · Physics 2016-01-13 Gregory D. Fleishman , Yan Xu , Gelu N. Nita , Dale E. Gary

Hinode's observations revealed a very dynamic and complex chromosphere. This require revisiting the assumption that the chromospheric footpoints of solar flares are areas where accelerated particles only lose energy due to collisions.…

Solar and Stellar Astrophysics · Physics 2010-11-04 Rim Turkmani , John Brown

Recently, a number of peculiar flares have been reported, which demonstrate significant non-thermal particle signatures with a low, if any, thermal emission, that implies close association of the observed emission with the primary energy…

X-ray observations are a direct diagnostic of fast electrons produced in solar flares, energized during the energy release process and directed towards the Sun. Since the properties of accelerated electrons can be substantially changed…

Solar and Stellar Astrophysics · Physics 2015-10-28 Natasha Jeffrey , Eduard Kontar , Gordon Emslie , Nicolas Bian

We carried out detailed analysis of X-ray and radio observations of a simple flare loop that occurred on 12th August 2002, with the impulsive hard X-ray (HXR) light curves dominated by a single pulse. The emission spectra of the early…

Solar and Stellar Astrophysics · Physics 2015-06-22 I. N. Sharykin , S. Liu , L. Fletcher

The generation of nonthermal electrons during solar flares plays a critical role in energy transport from the corona to the chromosphere, producing regions of observed intense X-ray emission. Turbulence in post-flare loops, particularly…

Solar and Stellar Astrophysics · Physics 2026-02-05 Clarissa Mora , Fabio Bacchini , Rony Keppens

Aims: We investigate the electron acceleration in convective electric fields of cascading magnetic reconnection in a flaring solar corona and show the resulting hard X-ray (HXR) radiation spectra caused by Bremsstrahlung for the coronal…

Solar and Stellar Astrophysics · Physics 2015-12-09 X. Zhou , J. Büchner , M. Barta , W. Gan , S. Liu