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Related papers: Modeling Spectral Variability of Prompt GRB Emissi…

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The spectral properties of a composite thermal emission arising from a relativistic expanding fireball can be remarkably different from the Planck function. We perform a detailed study of such a system to explore the features of the prompt…

High Energy Astrophysical Phenomena · Physics 2024-07-04 Soumya Gupta , Sunder Sahayanathan

Discerning the radiative dissipation mechanism for prompt emission in Gamma-Ray Bursts (GRBs) requires detailed spectroscopic modeling that straddles the $\nu F_{\nu}$ peak in the 100 keV - 1 MeV range. Historically, empirical fits such as…

For over two decades, gamma-ray burst (GRB) prompt emission spectra were modelled with smoothly-broken power laws (Band function), and a positive and tight correlation between the spectral rest-frame peak energy $E_p$ and the total…

High Energy Astrophysical Phenomena · Physics 2024-09-16 Alessio Mei , Gor Oganesyan , Samanta Macera

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent…

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

Ultra-relativistic motion and efficient conversion of kinetic energy to radiation are required by gamma-ray burst (GRB) observations, yet they are difficult to simultaneously achieve. Three leading mechanisms have been proposed to explain…

High Energy Astrophysical Phenomena · Physics 2016-04-06 Damien Bégué , J. Michael Burgess

The origin of prompt emission from gamma ray bursts remains to be an open question. Correlated prompt optical and gamma-ray emission observed in a handful of GRBs strongly suggests a common emission region, but failure to adequately fit the…

High Energy Astrophysical Phenomena · Physics 2016-12-21 S. Guiriec , C. Kouveliotou , D. H. Hartmann , J. Granot , K. Asano , P. Meszaros , R. Gill , N. Gehrels , J. McEnery

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.…

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

The radiative process responsible for gamma-Ray Burst (GRB) prompt emission has not been identified yet. If dominated by fast-cooling synchrotron radiation, the part of the spectrum immediately below the $\nu F_\nu$ peak energy should…

High Energy Astrophysical Phenomena · Physics 2017-09-20 Gor Oganesyan , Lara Nava , Giancarlo Ghirlanda , Annalisa Celotti

The prompt gamma-ray emission in gamma-ray bursts is believed to be produced by internal shocks within a relativistic unsteady outflow. The recent detection of prompt optical emission accompanying the prompt gamma-ray emission appears to be…

Astrophysics · Physics 2009-11-13 Zhuo Li , Eli Waxman

In this paper, we simulate the prompt emission light curves of gamma-ray bursts (GRBs) within the framework of the Internal-Collision-induced MAgnetic Reconnection and Turbulence (ICMART) model. This model applies to GRBs with a…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Bo Zhang , Bing Zhang

Many gamma ray bursts (GRBs) have been observed with the Burst-Alert and X-Ray telescopes of the Swift satellite. The successive `pulses' of these GRBs end with a fast decline and a fast spectral softening, until they are overtaken by…

Astrophysics · Physics 2009-11-13 Shlomo Dado , Arnon Dar , A. De Rujula

The prompt optical emission that arrives with gamma-rays from a cosmic gamma-ray burst (GRB) is a signature of the engine powering the burst, the properties of the ultra-relativistic ejecta of the explosion, and the ejecta's interactions…

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

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 debate regarding the emission mechanism in gamma-ray bursts has been long-standing. Here, we study the spectral signatures of photospheric emission, accounting for subphotospheric dissipation by a radiation-mediated shock. The shocks…

High Energy Astrophysical Phenomena · Physics 2024-07-15 Filip Alamaa , Felix Ryde , Christoffer Lundman

A substantial fraction of prompt GRB spectra have soft spectral indexes exceeding the maximum allowed by the synchrotron model alpha_{max}=-2/3. Some spectra also exhibit very sharp break at E_p, inconsistent with the smooth synchrotron…

Astrophysics · Physics 2009-11-10 Mikhail V. Medvedev

As gamma-ray burst (GRB) jet drills its way through the collapsing star, it traps a baryonic cork ahead of it. Here we explore a prompt emission model for GRBs in which the jet does not cross the cork, but rather photons that are emitted…

High Energy Astrophysical Phenomena · Physics 2021-03-11 Mukesh K Vyas , Asaf Pe'er , David Eichler

In the standard scenario of the fireball model of gamma-ray bursts(GRBs), the huge initial energy release produces a relativistic blast wave expanding into the external medium and a reverse shock moving into and heating the fireball ejecta.…

Astrophysics · Physics 2009-10-31 X. Y. Wang , Z. G. Dai , T. Lu