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We performed a time-resolved spectral analysis of 53 bright gamma-ray bursts (GRBs) observed by \textit{Fermi}/GBM. Our sample consists of 908 individual spectra extracted from the finest time slices in each GRB. We fitted them with the…

High Energy Astrophysical Phenomena · Physics 2022-03-02 Dao-Zhou Wang , Xiao-Hong Zhao , Zhao Zhang , Bin-Bin Zhang , Zhao-Yang Peng

To understand the physical mechanisms underlying the prompt emission of gamma-ray bursts (GRB), single FRED (Fast-Rise-Exponential-Decay) profile GRBs serve as an ideal sample, as they origin from single epoch central engine activity. These…

High Energy Astrophysical Phenomena · Physics 2026-03-24 Shu-Xu Yi , Chen-Wei Wang , Shao-Lin Xiong , Shuang-Nan Zhang , Romain Maccary , Rahim Moradi , Shuo Xiao , Hua Feng

The origin of prompt emission in $\gamma$-ray bursts (GRBs) is highly debated topic. The observed spectra are supposed to play a crucial role in constraining the location of the emitting region, the strength of the magnetic field and the…

High Energy Astrophysical Phenomena · Physics 2020-06-26 Gor Oganesyan

We explore fitting gamma-ray burst spectra with three physically-motivated models, and thus revisit the viability of synchrotron radiation as the primary source of GRB prompt emission. We pick a sample of 100 bright GRBs observed by the…

High Energy Astrophysical Phenomena · Physics 2023-11-23 Suraj Poolakkil , Robert Preece , Peter Veres

We aim to obtain a measure of the curvature of time-resolved spectra that can be compared directly to theory. This tests the ability of models such as synchrotron emission to explain the peaks or breaks of GBM prompt emission spectra. We…

The prompt phase X- and $\gamma$-ray light curves of gamma-ray bursts (GRBs) exhibit erratic and complex behaviour, often with multiple pulses. The temporal shape of individual pulses is often modelled as 'fast rise exponential decay'…

High Energy Astrophysical Phenomena · Physics 2025-07-14 A Gowri , A. Pe'er , F. Ryde , H. Dereli-Bégué

We investigate synchrotron emission models as the source of gamma-ray burst spectra. We show that including the possibility for synchrotron self-absorption, a ``smooth cutoff'' to the electron energy distribution, and an anisotropic…

Astrophysics · Physics 2018-11-06 Nicole M. Lloyd-Ronning , Vahe' Petrosian

The observational diversity of optical emission, which coincides with prompt gamma-ray bursts (GRBs), has been discovered in the recent Swift era. We show that on the assumption of the synchrotron radiation for the observed energy range…

Astrophysics · Physics 2009-11-13 Hirotsugu Doi , Kentaro Takami , Ryo Yamazaki

We study the time-resolved spectra of eight GRBs observed by Fermi GBM in its first five years of mission, with 1 keV - 1 MeV fluence $f>1.0\times10^{-4}$ erg cm$^{-2}$ and signal-to-noise level $\text{S/N}\geq10.0$ above 900 keV. We aim to…

Several trends have been identified in the prompt gamma-ray burst (GRB) emission: e.g. hard-to-soft evolution, pulse width evolution with energy, time lags, hardness-intensity/-fluence correlations. Recently Fermi has significantly extended…

High Energy Astrophysical Phenomena · Physics 2015-06-19 Z. Bosnjak , F. Daigne

The time-resolved spectra of gamma-ray bursts (GRBs) remain in conflict with many proposed models for these events. After proving that most of the bursts in our sample show evidence for spectral "shape-shifting", we discuss what…

Astrophysics · Physics 2009-10-30 A. Crider , E. P. Liang , R. D. Preece

We discuss the new surprising observational results that indicate quite convincingly that the prompt emission of Gamma-Ray Bursts (GRBs) is due to synchrotron radiation produced by a particle distribution that has a low energy cut-off. The…

High Energy Astrophysical Phenomena · Physics 2020-04-29 G. Ghisellini , G. Ghirlanda , G. Oganesyan , S. Ascenzi , L. Nava , A. Celotti , O. S. Salafia , E. M. Ravasio , M. Ronchi

The characteristics of the spectral evolution of the prompt emission of gamma-ray bursts (GRBs), which are closely related to the radiation mechanism (synchrotron or photosphere), are still an unsolved subject. Here, by performing the…

High Energy Astrophysical Phenomena · Physics 2019-11-12 Liang Li , Jin-Jun Geng , Yan-Zhi Meng , Xue-Feng Wu , Yong-Feng Huang , Yu Wang , Rahim Moradi , Z. Lucas Uhm , Bing Zhang

The discovery (Liang & Kargatis 1996), that the peak energy of time-resolved spectra of gamma-ray burst (GRB) pulses decays exponentially with fluence, is analytically shown to imply that the time-integrated photon number spectrum of a…

Astrophysics · Physics 2009-10-30 Felix Ryde , Roland Svensson

The prompt-emission spectra of gamma-ray bursts (GRBs) are commonly described by the empirical Band function. The typical low-energy spectral index is $\sim -1$, which poses a challenge to standard synchrotron radiation models. We…

High Energy Astrophysical Phenomena · Physics 2026-04-23 Jia-Ming Chen , Ke-Rui Zhu , Zhao-Yang Peng , Yong-Gang Zheng , Yun-Lu Gong , Shan Chang , Shi-Ting Tian , Li Zhang

The prompt emission of the long, smooth, and single-pulsed gamma-ray burst, GRB $\textit{141028A}$, is analyzed under the guise of an external shock model. First, we fit the $\gamma$-ray spectrum with a two-component photon model, namely…

High Energy Astrophysical Phenomena · Physics 2016-05-25 J. Michael Burgess , Damien Bégué , Felix Ryde , Nicola Omodei , Asaf Pe'er , J. L. Racusin , A. Cucchiara

In this paper, we explore time resolved Gamma-Ray Burst (GRB) spectra in the context of the synchrotron emission model presented in Lloyd and Petrosian (2000; LP00). First, we show that our model - which involves three distinct emission…

Astrophysics · Physics 2009-11-07 Nicole M. Lloyd-Ronning , Vahe' Petrosian

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

We perform a time-resolved spectral analysis of GRB 130606B within the framework of a fast-cooling synchrotron radiation model with magnetic field strength in the emission region decaying with time, as proposed by Uhm & Zhang. The data from…

High Energy Astrophysical Phenomena · Physics 2016-04-19 Bin-Bin Zhang , Z. Lucas Uhm , Valerie Connaughton , Michael S. Briggs , Bing Zhang

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
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