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Recent multi-wavelength observations of M87* \citep{2024A&A...692A.140A} revealed a high-energy $\gamma$-ray flare without a corresponding millimeter counterpart. We present a theoretical polarimetric study to evaluate the presence and…

Driven by recent RHESSI observations of confined loop-top hard X-ray sources in solar flares, we consider stochastic acceleration of electrons in the presence of Coulomb collisions. If electron escape from the acceleration region can be…

Solar and Stellar Astrophysics · Physics 2015-06-23 Nicolas H. Bian , A. Gordon Emslie , Duncan J. Stackhouse , Eduard P. Kontar

The dynamical responses of ferromagnet to the propagating electromagnetic field wave passing through it are modelled and studied here by Monte Carlo simulation in two dimensional Ising ferromagnet. Here, the electromagnetic wave is linearly…

Statistical Mechanics · Physics 2025-08-04 Muktish Acharyya

Solar flare electron acceleration is an extremely efficient process, but the method of acceleration is not well constrained. Two of the essential diagnostics: electron anisotropy (velocity angle to the guiding magnetic field) and the high…

Solar and Stellar Astrophysics · Physics 2020-12-21 Natasha L. S. Jeffrey , Pascal Saint-Hilaire , Eduard P. Kontar

We present observations of a confined M4.0 flare from NOAA 11302 on 2011 September 26. Observations at high temporal, spatial, and spectral resolution from Solar Dynamics Observatory, Reuven Ramaty High Energy Solar Spectroscopic Imager,…

Solar and Stellar Astrophysics · Physics 2014-08-05 Upendra Kushwaha , Bhuwan Joshi , Kyung-Suk Cho , Astrid Veronig , Sanjiv Kumar Tiwari , S. K. Mathew

We studied long duration flare observed with Nobeyama Radioheliograph at frequencies 17 and 34 GHz and with Ramaty High Energy Solar Spectroscopic Imager at 25-50 keV. We found that microwave and hard X-ray emission variation contain…

Solar and Stellar Astrophysics · Physics 2011-10-07 Veronika Reznikova , Kiyoto Shibasaki

Previous studies have shown that the energy release mechanism of some solar flares follow the Standard magnetic-reconnection model, but the detailed properties of high-energy electrons produced in the flare are still not well understood. We…

Solar and Stellar Astrophysics · Physics 2015-07-15 Natsuha Kuroda , Haimin Wang , Dale E. Gary

Electromagnetic waves propagate in the Schwarzschild spacetime like in a nonuniform medium with a varying refraction index. A fraction of the radiation scatters off the curvature of the geometry. The energy of the backscattered part of an…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Edward Malec

We present observations of electron energization in magnetic reconnection outflows during the pre-impulsive phase of solar flare SOL2012-07-19T05:58. During a time-interval of about 20 minutes, starting 40 minutes before the onset of the…

Solar and Stellar Astrophysics · Physics 2019-03-06 Marina Battaglia , Eduard P. Kontar , Galina Motorina

We investigate the reflection coefficient of spin waves propagating in an ultra-thin ferromagnetic film with regions where saturation magnetization is modulated. We find analytically and using micromagnetic simulations that there are…

Mesoscale and Nanoscale Physics · Physics 2020-01-08 Pablo Borys , Naser Qureshi , Cesar Ordonez-Romero , Oleg Kolokoltsev

Energetic electrons accelerated at coronal reconnection sites during solar flares precipitate into the lower solar atmosphere, generating nonthermal emissions and regulating energy deposition. However, how their transport and precipitation…

Solar and Stellar Astrophysics · Physics 2026-05-07 Feiyu Yu , Xiangliang Kong , Ze Zhong , Zhentong Li , Zelong Jiang , Yingli Cui , Zhao Wu , Yao Chen , Gang Li

Small-scale magnetic field concentrations (magnetic elements) in the quiet Sun are believed to contribute to the energy budget of the upper layers of the Sun's atmosphere, as they are observed to support a large number of MHD modes. In…

Solar and Stellar Astrophysics · Physics 2015-04-29 M. Stangalini , F. Giannattasio , S. Jafarzadeh

Soon after the discovery of radio pulsars in 1967, the pulsars are identified as strongly magnetic (typically $10^{12}$G) rapidly rotating ($\sim 10^{2}-0.1$ Hz) neutron stars. However, the mechanism of particle acceleration in the pulsar…

Astrophysics · Physics 2008-11-26 Tomohide Wada , Shinpei Shibata

Recent observations of high energy (> 20 keV) X-ray emission in a few clusters of galaxies broaden our knowledge of physical phenomena in the intracluster space. This emission is likely to be nonthermal, probably resulting from Compton…

Astrophysics · Physics 2009-11-13 Y. Rephaeli , J. Nevalainen , T. Ohashi , A. M. Bykov

Solar flares are associated with intense soft X-ray emission generated by the hot flaring plasma. Kink unstable twisted flux-ropes provide a source of magnetic energy which can be released impulsively and account for the flare plasma…

Solar and Stellar Astrophysics · Physics 2015-03-25 R. F. Pinto , N. Vilmer , A. S. Brun

Simultaneous simulation of HXR and MW emission with the same populations of electrons is still a great challenge for interpretation of observations in real events. In this paper we apply the FP kinetic model of precipitation of electron…

Solar and Stellar Astrophysics · Physics 2015-05-28 V. V. Zharkova , N. S. Meshalkina , L. K. Kashapova , A. A. Kuznetsov , A. T. Altyntsev

We perform direct numerical simulations of an externally driven two-dimensional magnetohydrodynamic system over extended periods of time to simulate the dynamics of a transverse section of a solar coronal loop. A stationary and large-scale…

Astrophysics · Physics 2009-10-30 Pablo Dmitruk , Daniel O. Gomez

We address a possibility of the flare process initiation and further maintenance of its energy release due to a transformation of sunspot longitudinal waves into transverse magnetic loop oscillations with initiation of reconnection. This…

Solar and Stellar Astrophysics · Physics 2015-05-20 R. Sych , M. Karlický , A. Altyntsev , J. Dudík , L. Kashapova

Context: Solar flares accelerate electrons, creating non-thermal energy distributions. However, the acceleration sites and dominant acceleration mechanisms remain largely unknown. Aims: We study the characteristics of electron acceleration…

Solar and Stellar Astrophysics · Physics 2025-11-12 Eilif S. Øyre , Boris V. Gudiksen , Lyndsay Fletcher

In this study, we investigate motions in the hot plasma above the flare loops during the 2017 September 10 X8.2 flare event. We examine the region to the south of the main flare arcade, where there is data from the Interface Region Imaging…

Solar and Stellar Astrophysics · Physics 2021-01-06 Katharine K. Reeves , Vanessa Polito , Bin Chen , Giselle Galan , Sijie Yu , Wei Liu , Gang Li