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Relativistic jets generated in gamma-ray bursts (GRBs) produce luminous transient events, yet the fundamentals of jet composition and radiation mechanisms remain unclear. One means of identifying a magnetically-dominated outflow would be…

Relations linking the temporal or/and spectral properties of the prompt emission of gamma-ray bursts (hereafter GRBs) to the absolute luminosity are of great importance as they both constrain the radiation mechanisms and represent potential…

High Energy Astrophysical Phenomena · Physics 2015-05-30 S. Boci , M. Hafizi , R. Mochkovitch

We make a detailed time resolved spectroscopy of bright long gamma ray bursts (GRBs) which show significant GeV emissions (GRB 080916C, GRB 090902B, and GRB 090926A). In addition to the standard Band model, we also use a model consisting of…

High Energy Astrophysical Phenomena · Physics 2017-02-22 A. R. Rao , Rupal Basak , J. Bhattacharya , S. Chandra , N. Maheshwari , M. Choudhury , Ranjeev Misra

We use the spectral lag data of 32 long GRBs detected by Fermi/GBM, which has been recently collated in Liu et al (2022) to quantify the statistical significance of a transition in the spectral lag data based on Lorentz invariance violation…

High Energy Astrophysical Phenomena · Physics 2023-10-18 Vibhavasu Pasumarti , Shantanu Desai

Using high-quality, broad-band afterglow data for GRB 091127, we investigate the validity of the synchrotron fireball model for gamma-ray bursts, and infer physical parameters of the ultra-relativistic outflow. We used multi-wavelength…

We study 7 Gamma Ray Bursts (GRBs), detected both by the BATSE instrument, on-board the Compton Gamma Ray Observatory, and by the Wide Field Camera (WFC), on-board BeppoSAX. These bursts have measured spectroscopic redshifts and are a…

Astrophysics · Physics 2009-06-23 G. Ghirlanda , Z. Bosnjak , G. Ghisellini , F. Tavecchio , C. Firmani

Photospheric (thermal) emission is inherent to the gamma-ray burst (GRB) "fireball" model. We show here, that inclusion of this component in the analysis of the GRB prompt emission phase naturally explains some of the prompt GRB spectra…

High Energy Astrophysical Phenomena · Physics 2015-05-19 Asaf Pe'er , Bin-Bin Zhang , Felix Ryde , Sinéad McGlynn , Bing Zhang , Robert D. Preece , Chryssa Kouveliotou

The physical origin of gamma-ray burst (GRB) prompt emission (photosphere or synchrotron) is still subject to debate after five decades. Here, firstly we find that many observed characteristics of 15 long GRBs, which have the highest prompt…

High Energy Astrophysical Phenomena · Physics 2022-12-13 Yan-Zhi Meng

The origins of the main burst and second burst of gamma-ray bursts (GRBs) and the composition of their jets remain uncertain. To explore this complex subject more thoroughly, we conduct a spectral analysis on 18 GRBs with a main and a…

High Energy Astrophysical Phenomena · Physics 2025-05-12 Ze-Lian Du , Zhao-Yang Peng , Jia-Ming Chen , Yue Yin , Ting Li

A small fraction of gamma-ray bursts (GRBs) exhibit blackbody emission in the X-ray spectra, the origin of which is debated. In order to gain a more complete understanding of this phenomenon, we present a search for blackbody components in…

High Energy Astrophysical Phenomena · Physics 2021-01-22 Vlasta Valan , Josefin Larsson

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

The sky distribution of Gamma-Ray Bursts (GRBs) has been intensively studied by various groups for more than two decades. Most of these studies test the isotropy of GRBs based on their sky number density distribution. In this work we…

High Energy Astrophysical Phenomena · Physics 2017-12-25 Jakub Ripa , Arman Shafieloo

The duration of more than one thousand gamma-ray bursts (GRBs) has been measured by Swift satellite. Besides the redshift distribution of GRBs, the burst duration could be another significant property of GRBs that can be analyzed. In this…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-28 Zeinab Kalantari , Sohrab Rahvar

Synchrotron polarization of relativistic nonthermal electrons in gamma-ray bursts (GRBs) has been widely studied. However, recent numerical simulations of relativistic shocks and magnetic reconnection have found that a more realistic…

High Energy Astrophysical Phenomena · Physics 2024-10-02 Kangfa Cheng , Jirong Mao , Xiaohong Zhao , Hongbang Liu , Merlin Kole , Nicolas Produit , Zhifu Chen

We call "prompt" emission of Gamma Ray Bursts (GRBs) the erratic and violent phase of hard X-ray and soft gamma-ray emission, usually lasting for tens of seconds in long GRBs. However, the central engine of GRBs may live much longer.…

Cosmology and Nongalactic Astrophysics · Physics 2009-08-07 G. Ghisellini , M. Nardini , G. Ghirlanda

A complete understanding of Gamma Ray Bursts (GRBs) has been difficult to achieve due to our incomplete knowledge of the radiation mechanism that is responsible for producing the prompt emission. This emission, which is detected in the…

High Energy Astrophysical Phenomena · Physics 2021-12-15 Tyler Parsotan , Davide Lazzati

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

We present a detail analysis on the spectral lags of the short gamma-ray bursts (GRBs) and compare them with that of the long GRBs by using the CGRO/BATSE GRB Catalog. Our results are as follows. (1)The spectral lag distribution of the…

Astrophysics · Physics 2009-11-11 Tingfeng Yi , Enwei Liang , Yiping Qin , Ruijing Lu

In gamma-ray bursts (GRBs), the electron pitch angle ($\alpha$) is usually assumed to be isotropically distributed. However, recent numerical simulations indicate that only the high-energy electrons (with Lorentz factors…

High Energy Astrophysical Phenomena · Physics 2026-04-27 Kang-Fa Cheng , Kai-Xian Luo , Xiao-Hong Zhao , Jirong Mao , Hong-Bang Liu , Yu-Hang Mo , Jin-Rong Huang , Rong-Li Weng , Wen-Jie Xie , Gao-Jin Yu

The gamma-ray burst GRB 180720B is very peculiar. On one hand, some interesting features have been found by performing the detailed time-resolved spectral analysis in the prompt phase. First, the `flux-tracking' pattern is exhibited both…

High Energy Astrophysical Phenomena · Physics 2019-12-24 Ming-Ya Duan , Xiang-Gao Wang