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The radiation process of GRB prompt emission remains highly debated till date. Though a smoothly broken powerlaw function like Band provides an excellent fit to most of the cases, a spectrum with a broad top or double hump structure has…

High Energy Astrophysical Phenomena · Physics 2018-02-07 R. Basak

We aim to investigate the ability of simple spectral models to describe the GRB early afterglow emission. We performed a time resolved spectral analysis of a bright GRB sample detected by the Swift Burst Alert Telescope and promptly…

We present a systematic analysis of the spectral and temporal properties of 17 GRBs co-detected by GBM and LAT on board the Fermi satellite by May 2010. We performed a time-resolved spectral analysis of all the bursts with the finest…

High Energy Astrophysical Phenomena · Physics 2011-03-17 Bin-Bin Zhang , Bing Zhang , En-Wei Liang , Yi-Zhong Fan , Xue-Feng Wu , Asaf Pe'er , Amanda Maxham , He Gao , Yun-Ming Dong

We present a powerful new tool for fitting broadband gamma-ray burst afterglow data, which can be used to determine the burst explosion parameters and the synchrotron radiation parameters. By making use of scale invariance between…

High Energy Astrophysical Phenomena · Physics 2015-05-30 H. J. van Eerten , A. J. van der Horst , A. I. MacFadyen

Long-lasting emission of short gamma-ray bursts (GRBs) is crucial to reveal the physical origin of the central engine as well as to detect electromagnetic (EM) counterparts to gravitational waves (GWs) from neutron star binary mergers. We…

High Energy Astrophysical Phenomena · Physics 2017-09-20 Shota Kisaka , Kunihito Ioka , Takanori Sakamoto

Traditionally gamma-ray bursts (GRBs) are classified in the $T_{90}$-hardness ratio two-dimensional plane into long/soft and short/hard GRBs. In this paper, we suggest to add the "amplitude" of GRB prompt emission as the third dimension as…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Hou-Jun Lü , Bing Zhang , En-Wei Liang , Bin-Bin Zhang , Takanori Sakamoto

The synchrotron shock model (SSM) for gamma-ray burst emission makes a testable prediction: that the observed low-energy power-law photon number spectral index cannot exceed -2/3 (where the photon model is defined with a positive index:…

Astrophysics · Physics 2009-10-30 R. D. Preece , M. S. Briggs , R. S. Mallozzi , G. N. Pendleton , W. S. Paciesas , D. L. Band

We examine a sample of 21 gamma-ray burst (GRB) afterglow light curves at radio frequencies, and compare them to the X-ray and/or optical properties of the afterglows and to the predictions of the standard jet/fireball model. Our sample…

High Energy Astrophysical Phenomena · Physics 2021-04-20 Tuomas Kangas , Andrew Fruchter

We consider the conditions within a Gamma-Ray Burst (GRB) emission region that is Poynting flux dominated. Due to the enormous magnetic energy density, relativistic electrons will cool in such a region extremely rapidly via synchrotron. As…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Paz Beniamini , Tsvi Piran

Spectral lag, the time difference between the arrival of high-energy and low-energy photons, is a common feature in Gamma-ray Bursts (GRBs). Norris et al. 2000 reported a correlation between the spectral lag and the isotropic peak…

High Energy Astrophysical Phenomena · Physics 2015-05-13 T. N. Ukwatta , M. Stamatikos , K. S. Dhuga , T. Sakamoto , S. D. Barthelmy , A. Eskandarian , N. Gehrels , L. C. Maximon , J. P. Norris , W. C. Parke

The site and mechanism of gamma-ray burst (GRB) prompt emission is still unknown. Although internal shocks have been widely discussed as the emission site of GRBs, evidence supporting other emission sites have been also suggested recently,…

Astrophysics · Physics 2015-05-13 Nayantara Gupta , Bing Zhang

Long-lived high-energy (>100MeV) emission, a common feature of most Fermi-LAT detected gamma-ray burst, is detected up to \sim 10^2 s in the short GRB 090510. We study the origin of this long-lived high-energy emission, using broad-band…

High Energy Astrophysical Phenomena · Physics 2015-05-19 Hao-Ning He , Xue-Feng Wu , Kenji Toma , Xiang-Yu Wang , Peter Meszaros

Gamma-ray bursts are most luminous explosions in the universe. Their ejecta are believed to move towards Earth with a relativistic speed. The interaction between this "relativistic jet" and a circum burst medium drives a pair of (forward…

High Energy Astrophysical Phenomena · Physics 2015-06-17 He Gao , Wei-Hua Lei , Yuan-Chuan Zou , Xue-Feng Wu , Bing Zhang

Simultaneous $\gamma$-ray measurements of gamma-ray burst (GRB) spectra and polarization offer a unique way to determine the underlying emission mechanism(s) in these objects as well as probing the particle acceleration mechanism(s) that…

High Energy Astrophysical Phenomena · Physics 2019-08-13 J. Michael Burgess , M. Kole , F. Berlato , J. Greiner , G. Vianello , N. Produit , Z. H Li , J. C Sun

Due to the lack of low redshift long Gamma-Ray Bursts (GRBs), the circular problem has been a severe obstacle for using GRBs as cosmological candles. In this paper, we present a new method to deal with such a problem in MCMC global fitting…

Astrophysics · Physics 2010-11-11 Hong Li , Jun-Qing Xia , Jie Liu , Gong-Bo Zhao , Zu-Hui Fan , Xinmin Zhang

The internal/external synchrotron shock scenario has proved very successful in interpreting the key observations about gamma ray bursts. There still remains, however, some big uncertainties. The hottest issue concerns the nature of the…

Astrophysics · Physics 2007-05-23 G. Ghisellini

We show that if the intrinsic break energy of Gamma-Ray Bursts (GRBs) is determined by the product of more than three random variables the observed break energy distribution becomes almost lognormal including the redshift effect because of…

Astrophysics · Physics 2009-11-07 Kunihito Ioka , Takashi Nakamura

We present a new technique to calculate the spectral lags of gamma-ray bursts (GRBs). Unlike previous processing methods, we first smooth the light curves of gamma-ray bursts in high and low energy bands using the "Loess" filter, then, we…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Zhao-sheng Li , Li Chen , De-hua Wang

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

Recent Fermi results have focused attention on gamma-ray burst's (GRB) prompt emission phase, which is rich in phenomenology and poorly understood. The broad band spectra observed by Fermi does not fit into any of the frameworks of existing…

High Energy Astrophysical Phenomena · Physics 2011-11-16 Asaf Pe'er
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