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Owing to narrow energy band of \textit{Swift}/BAT, several urgent issues are required to pay more attentions but unsolved so far. We systematically study the properties of a refined sample of 283 \textit{Swift}/BAT gamma-ray bursts with…

High Energy Astrophysical Phenomena · Physics 2021-08-30 Z. B. Zhang , M. Jiang , Y. Zhang , K. Zhang , X. J. Li , Q. Zhang

Understanding the origin and diversity of emission processes responsible for Gamma-ray Bursts (GRBs) remains a pressing challenge. While prompt and contemporaneous panchromatic observations have the potential to test predictions of the…

We report the discovery of a correlation among three prompt emission properties of GRBs. These are the isotropic peak luminosity L_iso, the peak energy of the time-integrated prompt emission spectrum E_pk, and the ``high signal" timescale…

Astrophysics · Physics 2009-11-11 C. Firmani , G. Ghisellini , V. Avila-Reese , G. Ghirlanda

Recent advances in fitting prompt emission spectra in gamma-ray bursts (GRBs) are boosting our understanding of the still elusive origin of this radiation. These progresses have been possible thanks to a more detailed analysis of the…

High Energy Astrophysical Phenomena · Physics 2018-02-07 Lara Nava , Gor Oganesyan , Maria E. Ravasio , Lorenzo Amati , Giancarlo Ghirlanda , Paul O'Brien , Julian P. Osborne , Richard Willingale

Many different physical processes have been suggested to explain the prompt gamma-ray emission in gamma-ray bursts (GRBs). Although there are examples of both bursts with photospheric and synchrotron emission origins, these distinct…

High Energy Astrophysical Phenomena · Physics 2018-02-07 Zeynep Acuner , Felix Ryde

We demonstrate that the rapid spectral variability of prompt GRBs is an inherent property of radiation emitted from shock-generated, highly anisotropic small-scale magnetic fields. We interpret the hard-to-soft evolution and the correlation…

Astrophysics · Physics 2009-11-11 Mikhail V. Medvedev

Gamma-ray bursts (GRBs) are luminous stellar explosions characterized by the ejection of relativistic jets. This work proposes a novel paradigm to study these GRB jets. By analyzing the timing information of prompt pulses and X-ray flares,…

The origin of the prompt emission in gamma-ray bursts (GRBs) is still an unsolved problem and several different mechanisms have been suggested. Here we fit Fermi GRB data with a photospheric emission model which includes dissipation of the…

High Energy Astrophysical Phenomena · Physics 2015-09-30 Björn Ahlgren , Josefin Larsson , Tanja Nymark , Felix Ryde , Asaf Pe'er

The mechanism that causes the prompt-emission episode of gamma-ray bursts (GRBs) is still widely debated despite there being thousands of prompt detections. The favoured internal shock model relates this emission to synchrotron radiation.…

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…

We compare the prompt intrinsic spectral properties of a sample of short Gamma--ray Burst (GRB) with the first 0.3 seconds (rest frame) of long GRBs observed by Fermi/GBM. We find that short GRBs and the first part of long GRBs lie on the…

The emission process responsible for the so-called "prompt" emission of gamma-ray bursts is still unknown. A number of empirical models fitting the typical spectrum still lack a satisfactory interpretation. A few GRB spectral catalogues…

High Energy Astrophysical Phenomena · Physics 2011-05-03 C. Guidorzi , M. Lacapra , F. Frontera , E. Montanari , L. Amati , F. Calura , L. Nicastro , M. Orlandini

We compare the spectral properties of 79 short and 79 long Gamma-Ray Bursts (GRBs) detected by BATSE and selected with the same limiting peak flux. Short GRBs have a low-energy spectral component harder and a peak energy slightly higher…

High Energy Astrophysical Phenomena · Physics 2009-11-13 G. Ghirlanda , L. Nava , G. Ghisellini , A. Celotti , C. Firmani

The observed delay in the arrival times between high and low energy photons in gamma-ray bursts (GRBs) has been shown by Norris et al. to be correlated to the absolute luminosity of a GRB. Despite the apparent importance of this spectral…

Astrophysics · Physics 2009-11-07 D. Kocevski , E. P. Liang

The origins of Gamma-ray Burst prompt emission are currently not well understood and in this context long, well-observed events are particularly important to study. We present the case of GRB 070616, analysing the exceptionally…

The prompt emission of most gamma-ray bursts (GRBs) typically exhibits a non-thermal Band component. The synchrotron radiation in the popular internal shock model is generally put forward to explain such a non-thermal component. However,…

High Energy Astrophysical Phenomena · Physics 2021-09-17 Kai Wang , Zi-Gao Dai

We study time-resolved spectra of the prompt emission of Swift Gamma-ray bursts (GRB). Our goal is to see if previous BATSE claims of the existence of a large amount of spectra with the low energy photon indices harder than 2/3 are…

High Energy Astrophysical Phenomena · Physics 2015-05-13 V. Savchenko , A. Neronov

Gamma-ray bursts are usually classified through their high-energy emission into short-duration and long-duration bursts, which presumably reflect two different types of progenitors. However, it has been shown on statistical grounds that a…

Data from the 3B Catalogue suggest that short and long GRB are the results of different classes of events, rather than different parameter values within a single class: Short bursts have harder spectra in the BATSE bands, but chiefly long…

Astrophysics · Physics 2007-05-23 J. I. Katz , L. M. Canel

Traditionally, gamma-ray bursts (GRBs) are classified as long and short GRBs, with $T_{90} = 2$ s being the threshold duration. Generally, long-duration GRBs (LGRBs, $T_{90}>2$ s) are associated with the collapse of massive stars, and…

High Energy Astrophysical Phenomena · Physics 2024-10-03 Si-Yuan Zhu , Pak-Hin Thomas Tam