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We introduce a simple model to explain the time-reversed and stretched residuals in gamma-ray burst (GRB) pulse light curves. In this model an impactor wave in an expanding GRB jet accelerates from subluminal to superluminal velocities, or…

High Energy Astrophysical Phenomena · Physics 2019-10-02 Jon Hakkila , Robert Nemiroff

We use a parent sample of 118 gamma-ray burst (GRB) afterglows, with known redshift and host galaxy extinction, to separate afterglows with and without signatures of dominant reverse-shock emission and to determine which physical conditions…

High Energy Astrophysical Phenomena · Physics 2015-06-18 J. Japelj , D. Kopac , S. Kobayashi , R. Harrison , C. Guidorzi , F. J. Virgili , C. G. Mundell , A. Melandri , A. Gomboc

Many cosmological models of gamma-ray bursts (GRBs) assume that a single relativistic shell carries kinetic energy away from the source and later converts it into gamma rays, perhaps by interactions with the interstellar medium or by shocks…

Astrophysics · Physics 2007-05-23 M. C. Sumner , E. E. Fenimore

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

High energy emission (> tens MeV) of Gamma-Ray Bursts (GRBs) provides an important clue to understand the physical processes involved in GRBs, which may be correlated with the GRB early afterglow. A shallow decline phase has been well…

Astrophysics · Physics 2014-10-13 Da-Ming Wei , Yi-Zhong Fan

Fireball model of the gamma-ray bursts (GRBs) predicts generation of numerous internal shocks, which efficiently accelerate charged particles and generate relatively small-scale stochastic magnetic and electric fields. The accelerated…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Gregory D. Fleishman , Fedor A. Urtiev

The Fermi Large Area Telescope (Fermi-LAT) Collaboration reported the Second Gamma-ray Burst Catalog (2FLGC), which comprises a subset of 29 bursts with photon energies above 10 GeV. Although the standard synchrotron forward-shock model has…

High Energy Astrophysical Phenomena · Physics 2022-08-17 N. Fraija , M. G. Dainotti , S. Ugale , D. Jyoti , D. C. Warren

Synchrotron self-Compton (SSC) process in the reverse shocks of gamma-ray bursts is suggested to be responsible for the observed prompt high-energy gamma-ray emissions from several gamma-ray bursts. We find that the SSC emission from the…

Astrophysics · Physics 2007-05-23 X. Y. Wang , Z. G. Dai , T. Lu

Understanding of the nature of gamma-ray bursts (GRBs) is one of the challenging problem facing the astrophysics community. The field of gamma ray bursts is a rapidly developing one and we expect that new missions, like SWIFT and GLAST will…

Astrophysics · Physics 2008-11-26 A. Lazarian , V. Petrosian , H. Yan , J. Cho

The dissipation mechanism that powers gamma-ray bursts (GRBs) remains uncertain almost half a century after their discovery. The two main competing mechanisms are the extensively studied internal shocks and the less studied magnetic…

High Energy Astrophysical Phenomena · Physics 2016-06-07 Jonathan Granot

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 Gamma-Ray Bursts - GRBs are one of the most energetic astronomical events in the universe that have not yet an adequate explanation of what kind of mechanism is carried out. This question motivates the astronomical community to do…

High Energy Astrophysical Phenomena · Physics 2013-07-05 Camilo Delgado-Correal

Conventionally, long GRBs are thought to be caused by the core collapses of massive stars. During the lifetime of a massive star, a stellar wind bubble environment should be produced. Furthermore, the microphysics shock parameters may vary…

High Energy Astrophysical Phenomena · Physics 2015-05-14 S. W. Kong , A. Y. L. Wong , Y. F. Huang , K. S. Cheng

We discuss the implications of Fermi/LAT observations on several aspects of gamma-ray burst (GRB) physics, including the radiation process, the emission sites, the bulk Lorentz factor, and the pre-shock magnetic field: (1) MeV-range…

High Energy Astrophysical Phenomena · Physics 2012-01-04 Zhuo Li

The low-energy spectra of gamma-ray bursts' (GRBs) prompt emission are closely related to the energy distribution of electrons, which is further regulated by their cooling processes. We develop a numerical code to calculate the evolution of…

High Energy Astrophysical Phenomena · Physics 2018-01-16 Jin-Jun Geng , Yong-Feng Huang , Xue-Feng Wu , Bing Zhang , Hong-Shi Zong

Gamma-ray bursts (GRBs) are among the most luminous electromagnetic transients in the universe, providing unique insights into extreme astrophysical processes and serving as promising probes for cosmology. Unlike Type Ia supernovae, which…

High Energy Astrophysical Phenomena · Physics 2025-01-28 Chen Deng , Yong-Feng Huang , Fan Xu , Abdusattar Kurban

We investigate the expected radio emission from the reverse shock of short GRBs, using the afterglow parameters derived from the observed short GRB light curves. In light of recent results suggesting that in some cases the radio afterglow…

High Energy Astrophysical Phenomena · Physics 2018-11-06 Nicole M. Lloyd-Ronning

Gamma-ray bursts (GRBs) are cosmic events occurring at large distances beyond our galaxy. They provide a unique opportunity to study electromagnetic patterns not seen elsewhere. When the collimated GRB outflow interacts with the outer…

Gamma-ray bursts (GRBs) are spectacularly energetic events, with the potential to inform on the early universe and its evolution, once their redshifts are known. Unfortunately, determining redshifts is a painstaking procedure requiring…

Prompt {\gamma}-ray emissions from gamma-ray bursts (GRBs) exhibit a vast range of extremely complex temporal structures with a typical variability time-scale significantly short - as fast as milliseconds. This work aims to investigate the…

High Energy Astrophysical Phenomena · Physics 2011-09-28 G. Greco , R. Rosa , G. Beskin , S. Karpov , L. Romano , A. Guarnieri , C. Bartolini , R. Bedogni