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The multiwavelength observations of GRB afterglows, together with some high-performance particle-in-cell simulations, hint that the magnetic field may decay behind the shock front. In this work, we develop a numerical code to calculate the…

High Energy Astrophysical Phenomena · Physics 2023-02-17 Yan Huang , Zhuo Li

The long standing problem of identifying the emission mechanism operating in gamma-ray bursts (GRBs) has produced a myriad of possible models that have the potential of explaining the observations. Generally, the empirical Band function is…

High Energy Astrophysical Phenomena · Physics 2014-10-29 J. Michael Burgess , Felix Ryde , Hoi-Fung Yu

The analysis of gamma-ray burst (GRB) spectra often relies on empirical models lacking a distinct physical explanation. Previous attempts to couple physical models with observed data focus on individual burst studies, fitting models to…

High Energy Astrophysical Phenomena · Physics 2024-02-20 Zhen-Yu Yan , Jun Yang , Xiao-Hong Zhao , Yan-Zhi Meng , Bin-Bin Zhang

When an emitting spherical shell with a constant Lorentz factor turns off emission abruptly at some radius, its high-latitude emission would obey the relation of $\hat{\alpha}$ (the temporal index) = $2 + \hat{\beta}$ (the spectral index).…

High Energy Astrophysical Phenomena · Physics 2018-01-16 Jin-Jun Geng , Yong-Feng Huang , Zi-Gao Dai

The synchrotron external shock model predicts the evolution of the spectral ($\beta$) and temporal ($\alpha$) indices during the gamma-ray burst (GRB) afterglow for different environmental density profiles, electron spectral indices,…

High Energy Astrophysical Phenomena · Physics 2019-10-15 Donggeun Tak , Nicola Omodei , Z. Lucas Uhm , Judith Racusin , Katsuaki Asano , Julie McEnery

We present time resolved spectral analysis of prompt emission from GRB 160625B, one of the brightest bursts ever detected by Fermi in its nine years of operations. Standard empirical functions fail to provide an acceptable fit to the GBM…

High Energy Astrophysical Phenomena · Physics 2018-05-30 M. E. Ravasio , G. Oganesyan , G. Ghirlanda , L. Nava , G. Ghisellini , A. Pescalli , A. Celotti

The recent launches of the Einstein Probe (EP) and the Space Variable Objects Monitor (SVOM) mission have led to the detection of a growing number of long GRBs with significant, early soft X-ray flux during their gamma-ray emission,…

High Energy Astrophysical Phenomena · Physics 2025-10-21 Ziming Wang , Chenyu Wang , He Gao , Hua Feng , An Li , Lin Lin , Songyu Shen

Detailed information on the physical parameters in the sources of cosmological Gamma-Ray Bursts (GRBs) is obtained from few plausible assumptions consistent with observations. Model-independent requirements posed by these assumptions on the…

Astrophysics · Physics 2009-10-31 E. V. Derishev , V. V. Kocharovsky , Vl. V. Kocharovsky

Gamma-ray bursts (GRBs), among the most compelling astrophysical phenomena, are potential candidates for exploring the evolution of energy distribution among magnetic fields and particles through multiwavelength observations. The fraction…

High Energy Astrophysical Phenomena · Physics 2025-12-18 Nissim Fraija , Boris Betancourt-Kamenetskaia , Antonio Galván , Maria Dainotti

Although the physical origin of prompt emission in gamma-ray bursts (GRBs) remains inconclusive, previous studies have considered the synchrotron radiation of relativistic electrons as a promising mechanism. These works usually adopted a…

High Energy Astrophysical Phenomena · Physics 2020-04-22 Kuan Liu , Da-Bin Lin , Kai Wang , Li Zhou , Xiang-Gao Wang , En-Wei Liang

We calculate the synchrotron self-Compton emission from internal shocks occurring in relativistic winds as a source of gamma-ray bursts, with allowance for self-absorption. For plausible model parameters most pulses within a Gamma-Ray Burst…

Astrophysics · Physics 2009-10-31 A. Panaitescu , P. Meszaros

Although the physical origin of gamma-ray burst (GRB) prompt emission is still controversial, synchrotron radiation from accelerated electrons is a promising mechanism. It is believed that electrons are accelerated continuously by…

High Energy Astrophysical Phenomena · Physics 2019-06-05 Yue Zhang , Jin-Jun Geng , Yong-Feng Huang

This paper presents simulations of the synchrotron self-Compton (SSC) spectrum within the Internal-Collision-induced Magnetic Reconnection and Turbulence (ICMART) model. We investigate how key parameters like the magnetization $\sigma_0$…

High Energy Astrophysical Phenomena · Physics 2026-02-16 Xueying Shao , He Gao

Synchrotron radiation from a decelerating blastwave is a widely accepted model of radio to X-ray afterglow emission from gamma-ray bursts (GRBs). GeV gamma-ray emission detected by the Fermi Large Area Telescope (LAT) and the duration of…

High Energy Astrophysical Phenomena · Physics 2021-06-24 Jagdish C. Joshi , Soebur Razzaque

Energetic GeV photons expected from the closest and the most energetic Gamma-ray bursts (GRBs) provide an unique opportunity to study the very-high-energy emission as well as the possible correlations with lower energy bands in realistic…

High Energy Astrophysical Phenomena · Physics 2024-09-19 Nissim Fraija , P. Veres , B. Betancourt Kamenetskaia , A. Galvan-Gamez , M. G. Dainotti , Simone Dichiara , R. L. Becerra

There are two different evolution patterns of the peak energy ($E_\text{p}$) exhibited during the prompt emission phase of gamma-ray bursts (GRBs), i.e., hard-to-soft and intensity-tracking, of which the physical origin remains unknown.…

High Energy Astrophysical Phenomena · Physics 2021-12-20 Hao-Xuan Gao , Jin-Jun Geng , Yong-Feng Huang

Synchrotron circular polarization of a non-thermal power-law electron distribution in gamma-ray bursts (GRBs) has been studied. However, some numerical simulations have shown that the resulting distribution of electrons is a combination of…

High Energy Astrophysical Phenomena · Physics 2025-05-29 Kangfa Cheng , Jirong Mao , Xiaohong Zhao , Hongbang Liu , Zhegeng Chen , Gaojin Yu , Zhifu Chen

We discuss the prompt emission of Gamma-Ray Bursts in different spectral energy bands. First, we suggest that a three-part synchrotron emission model is a good description of the ~20 keV - 1 MeV gamma-ray emission of GRBs. We show that this…

Astrophysics · Physics 2009-11-07 Nicole M. Lloyd-Ronning

A leading mechanism for producing cosmological gamma-ray bursts (GRBs) is via ultra-relativistic particles in an expanding fireball. The kinetic energy of the particles is converted into thermal energy in a forward shock and a reverse…

Astrophysics · Physics 2009-10-28 Re'em Sari , Ramesh Narayan , Tsvi Piran

Gamma-ray bursts are the most energetic electromagnetic sources in the Universe. Their prompt gamma-ray radiation corresponds to an energy release of 1E42-1E47J. Fifty years after their discovery and several dedicated space-based…

High Energy Astrophysical Phenomena · Physics 2019-10-22 J. Michael Burgess , Damien Bégué , Ana Bacelj , Dimitrios Giannios , Francesco Berlato , Jochen Greiner