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Gamma-ray bursts (GRBs) show different behaviours and trends in their spectral evolution. One of the methods used to understand the physical origin of these behaviours is to study correlation between the spectral fit parameters. In this…

High Energy Astrophysical Phenomena · Physics 2020-06-09 Hüsne Dereli Bégué , Hoi-Fung Yu , Felix Ryde

Gamma Ray Bursts (GRBs) are notorious for their diversity. Yet, they have a series of common features. The typical energy of their $\gamma$ rays is a fraction of an MeV. The energy distributions are well described by a ``Band spectrum'',…

Astrophysics · Physics 2009-11-10 Arnon Dar , A. De Rujula

The analysis of gamma-ray burst (GRB) spectra with multi-component emission models has become an important part of the field. In particular, multi-component analysis where one component is a blackbody representing emission from a…

High Energy Astrophysical Phenomena · Physics 2015-05-27 J. Michael Burgess , Felix Ryde

With the early afterglow localizations of gamma-ray burst positions made by Swift, the clear delimitation of the prompt phase and the afterglow is not so obvious any more. It is important to see weather the two phases have the same origin…

High Energy Astrophysical Phenomena · Physics 2010-08-04 Péter Veres , Zsolt Bagoly

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

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

Temporal and spectral information extracted from a stream of photons received from astronomical sources is the foundation on which we build understanding of various objects and processes in the Universe. Typically astronomers fit a number…

High Energy Astrophysical Phenomena · Physics 2016-11-18 T. N. Ukwatta , P. R. Wozniak

Gamma-ray bursts (GRBs) are highly variable and exhibit strong spectral evolution. In particular, the emission properties vary from pulse to pulse in multipulse bursts. Here we present a time-resolved Bayesian spectral analysis of a…

High Energy Astrophysical Phenomena · Physics 2021-12-20 Liang Li , Felix Ryde , Asaf Pe'er , Hoi-Fung Yu , Zeynep Acuner

In the external shock model, gamma-ray burst (GRB) emissions are produced by the energization and deceleration of a thin relativistic blast wave due to its interactions with the circumburst medium (CBM). We study the physical properties of…

Astrophysics · Physics 2009-10-31 Charles D. Dermer , Markus Boettcher , J. Chiang

Gamma-ray bursts (GRBs) are intense pulses of high-energy emission associated with massive stars' death or compact objects' coalescence. Their multi-wavelength observations help verify the reliability of the standard fireball model. We…

High Energy Astrophysical Phenomena · Physics 2024-11-19 M. G. Dainotti , S. Bhardwaj , E. Bissaldi , N. Fraija , S. Sourav , A. Galvan-Gamez

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

A multivariate analysis of gamma-ray burst (GRB) bulk properties is presented to discriminate between distinct classes of GRBs. Several variables representing burst duration, fluence and spectral hardness are considered. Two multivariate…

Most of proposed models of cosmological gamma-ray bursts (GRBs) are associated to gravitational collapses of massive stars, and hence evolution of the GRB rate, which is crucially important in GRB intensity distribution analysis, is…

Astrophysics · Physics 2007-05-23 Tomonori TOTANI

Gamma-ray bursts (GRBs) are cosmological explosions which carry valuable information from the distant past of the expanding universe. One of the greatest discoveries in modern cosmology is the finding of the accelerated expansion of the…

High Energy Astrophysical Phenomena · Physics 2016-06-15 Rupal Basak , A. R. Rao

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

This paper presents a study on the spectral evolution of gamma-ray burst (GRB) prompt emissions observed with the Suzaku Wide-band All-sky Monitor (WAM). By making use of the WAM data archive, 6 bright GRBs exhibiting 7 well-separated…

High Energy Astrophysical Phenomena · Physics 2015-05-30 Makoto S. Tashiro , Kaori Onda , Kazutaka Yamaoka , Masahiro Ohno , Satoshi Sugita , Takeshi Uehara , Hiromi Seta

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

Gamma-ray bursts (GRB) are extremely energetic events and produce highly diverse light curves. Light curves are believed to be resulting from internal shocks reflecting the activities of the GRB central engine. Hence their temporal studies…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Narayana P. Bhat

We present the systematic spectral analyses of gamma-ray bursts (GRBs) detected by the Fermi Gamma-Ray Burst Monitor (GBM) during its first ten years of operation. This catalog contains two types of spectra; time-integrated spectral fits…

During the past ten years, the predictions of the cannonball (CB) model of gamma ray bursts (GRBs) were repeatedly confronted with the mounting data from space- and ground-based observations of GRBs and their afterglows (AGs). The two…

High Energy Astrophysical Phenomena · Physics 2015-05-13 Shlomo Dado , Arnon Dar