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Applying our recently-developed generalized version of the high-latitude emission theory to the observations of X-ray flares in gamma-ray bursts (GRBs), we present here clear observational evidence that the X-ray flare emission region is…

High Energy Astrophysical Phenomena · Physics 2016-06-15 Z. Lucas Uhm , Bing Zhang

Radiation from GRBs in the prompt phase, flares and an afterglow is thought to be produced by accelerated electrons in magnetic fields. Such emission may be produced at collisionless shocks of baryonic outflows or at reconnection sites (at…

High Energy Astrophysical Phenomena · Physics 2009-06-25 Mikhail V. Medvedev

The second brightest GRB in history, GRB230307A, provides an ideal laboratory to study the mechanism of GRB prompt emission thanks to its extraordinarily high photon statistics and its single episode activity. Here we demonstrate that the…

GRB 120308A, a long duration $\gamma-$ray burst detected by {\it Swift}, was distinguished by a highly-polarized early optical afterglow emission that strongly suggests an ordered magnetic field component in the emitting region. In this…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Shuai Zhang , Zhi-Ping Jin , Da-Ming Wei

One of the key open question in the study of jets in general, and jets in gamma-ray bursts (GRBs) in particular, is the magnetization of the outflow. Here we consider the photospheric emission of Poynting flux dominated outflows, when the…

High Energy Astrophysical Phenomena · Physics 2015-06-23 D. Bégué , A. Pe'er

Previous studies have considered synchrotron as the emission mechanism for prompt Gamma-Ray Bursts (GRBs). These works have shown that the electrons must cool on a timescale comparable to the dynamic time at the source in order to satisfy…

High Energy Astrophysical Phenomena · Physics 2018-02-28 Paz Beniamini , Rodolfo Barniol Duran , Dimitrios Giannios

In recent years, our understanding of gamma-ray bursts (GRB) prompt emission has been revolutionized, due to a combination of new instruments, new analysis methods and novel ideas. In this review, I describe the most recent observational…

High Energy Astrophysical Phenomena · Physics 2015-09-23 Asaf Pe'er

Even though the observed spectra for GRB prompt emission is well constrained, no single radiation mechanism can robustly explain its distinct non-thermal nature. Here we explore the radiation mechanism with the photospheric emission model…

High Energy Astrophysical Phenomena · Physics 2020-08-10 Mukul Bhattacharya , Pawan Kumar

Synchrotron radiation from accelerated electrons above the photosphere of a relativistic ejecta is a natural candidate for the dominant process for the prompt GRB emission. There is however a tension between the predicted low-energy…

High Energy Astrophysical Phenomena · Physics 2025-01-29 Frédéric Daigne , Željka Bošnjak

The existence of strong correlation between the peak luminosity (and/or bolometric energetics) of Gamma Ray Bursts (GRB) is one of the most intrigue problem of GRB physics. This correlation is not yet understood. Here we demonstrate that…

Astrophysics · Physics 2007-08-22 M. Yu. Piotrovich , Yu. N. Gnedin , T. M. Natsvlishvili

The energy dissipation mechanism within Gamma-Ray Burst (GRB) outflows, driving their extremely luminous prompt $\gamma$-ray emission is still uncertain. The leading candidates are internal shocks and magnetic reconnection. While the…

High Energy Astrophysical Phenomena · Physics 2016-05-13 Paz Beniamini , Jonathan Granot

The dissipation mechanism that powers gamma-ray bursts (GRBs) remains uncertain almost half a century after their discovery. The two main competing mechanisms are the extensively studied internal shocks and the less studied magnetic…

High Energy Astrophysical Phenomena · Physics 2016-06-07 Jonathan Granot

The dominant radiation mechanism that produces the prompt emission in gamma-ray bursts (GRBs) remains a major open question. Spectral information alone has proven insufficient in elucidating its nature. Time-resolved linear polarization has…

High Energy Astrophysical Phenomena · Physics 2021-04-21 Ramandeep Gill , Jonathan Granot

Optical re-brightenings in the afterglows of some gamma-ray bursts (GRBs) are unexpected within the framework of the simple external shock model. While it has been suggested that the central engines of some GRBs are newly born magnetars, we…

High Energy Astrophysical Phenomena · Physics 2017-05-11 J. J. Geng , X. F. Wu , Y. F. Huang , L. Li , Z. G. Dai

We present the analysis of the extraordinarily bright Gamma-Ray Burst (GRB) 130427A under the hypothesis that the GRB central engine is an accretion-powered magnetar. In this framework, initially proposed to explain GRBs with precursor…

The composition of relativistic outflows producing gamma-ray bursts is a long standing open question. One of the main arguments in favor of magnetically dominated outflows is the absence of photospheric component in their broadband time…

High Energy Astrophysical Phenomena · Physics 2022-03-30 Gregory Vereshchagin , Liang Li , Damien Bégué

The radiation released at the transparency radius of an ultrarelativistic flow can account for the observed properties of gamma-ray bursts (GRBs) provided that sufficient energy is dissipated in the sub-photospheric region. Here, I…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Dimitrios Giannios

Observations by the {\RHESSI} satellite of large polarization of the prompt $\gamma$-ray emission from the Gamma Ray Burst GRB021206 \citep{coburn03} imply that the magnetic field coherence scale is larger than the size of the visible…

Astrophysics · Physics 2009-11-07 Maxim Lyutikov , V. I. Pariev , Roger Blandford

In this work we numerically calculate the thermal radiation efficiency of the baryonic outflow. The possible outflow acceleration in the transparent stage, which lowers thermal radiation efficiency, has been taken into account. In the…

Cosmology and Nongalactic Astrophysics · Physics 2011-04-07 Yi-Zhong Fan

We consider a model in which the ultra-relativistic jet in a gamma-ray burst (GRB) is cold and magnetically accelerated. We assume that the energy flux in the outflowing material is partially thermalized via internal shocks or a reverse…

High Energy Astrophysical Phenomena · Physics 2015-05-28 Ramesh Narayan , Pawan Kumar , Alexander Tchekhovskoy