Time-resolved analysis of fermi gamma-ray bursts with fast- and slow-cooled synchrotron photon models
J. M. Burgess,Robert D. Preece,Valerie Connaughton,Michael S. Briggs,Adam Goldstein,P. N. Bhat,Jochen Greiner,David Gruber,Andreas von Kienlin,Chryssa Kouveliotou,Sinéad McGlynn,Charles A. Meegan,W. S. Paciesas,Arne Rau,Shaolin Xiong,Magnus Axelsson,Magnus Axelsson,Matthew G. Baring,Charles D. Dermer,Shabnam Iyyani,D. Kocevski,Nicola Omodei,Felix Ryde,Felix Ryde,Giacomo Vianello +24 more
TLDR
In this paper, the authors used the Fermi Gamma-Ray Space Telescope (GRSST) for time-resolved spectroscopy on eight bright, long gamma-ray bursts (GRBs) dominated by single emission pulses.Abstract:
Time-resolved spectroscopy is performed on eight bright, long gamma-ray bursts (GRBs) dominated by single emission pulses that were observed with the Fermi Gamma-Ray Space Telescope. Fitting the prompt radiation of GRBs by empirical spectral forms such as the Band function leads to ambiguous conclusions about the physical model for the prompt radiation. Moreover, the Band function is often inadequate to fit the data. The GRB spectrum is therefore modeled with two emission components consisting of optically thin non-thermal synchrotron radiation from relativistic electrons and, when significant, thermal emission from a jet photosphere, which is represented by a blackbody spectrum. To produce an acceptable fit, the addition of a blackbody component is required in five out of the eight cases. We also find that the low-energy spectral index α is consistent with a synchrotron component with α = –0.81 ± 0.1. This value lies between the limiting values of α = –2/3 and α = –3/2 for electrons in the slow- and fast-cooling regimes, respectively, suggesting ongoing acceleration at the emission site. The blackbody component can be more significant when using a physical synchrotron model instead of the Band function, illustrating that the Band function does not serve as a good proxy for a non-thermal synchrotron emission component. The temperature and characteristic emission-region size of the blackbody component are found to, respectively, decrease and increase as power laws with time during the prompt phase. In addition, we find that the blackbody and non-thermal components have separate temporal behaviors as far as their respective flux and spectral evolutions.read more
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Fast-cooling synchrotron radiation in a decaying magnetic field and γ-ray burst emission mechanism
TL;DR: In this article, it was shown that in a certain parameter regime, the fast-cooling electrons can have a harder energy spectrum than the fast cooling electrons in a decaying magnetic field, and it was suggested that the GRB prompt emission spectra whose low-energy photon spectral index has a typical value 2,3,4,5−1 could be due to synchrotron radiation in this moderately fast cooling regime.
Journal ArticleDOI
Synchrotron origin of the typical grb band function—a case study of grb 130606b
TL;DR: In this paper, a time-resolved spectral analysis of GRB 130606B was performed under the framework of a fast-cooling synchrotron radiation model with magnetic field strength in the emission region decaying with time.
Journal ArticleDOI
Physics of Gamma-Ray Bursts Prompt Emission
TL;DR: In this article, the authors describe the most recent observational results and current theoretical interpretation of gamma-ray bursts and highlight some areas of active theoretical research, including the role played by magnetic fields in shaping the dynamics of GRB outflow and spectra, and the microphysics of kinetic and magnetic energy.
Journal ArticleDOI
The Fermi GBM gamma-ray burst time-resolved spectral catalog: brightest bursts in the first four years
Hoi-Fung Yu,Robert D. Preece,Jochen Greiner,P. Narayana Bhat,Elisabetta Bissaldi,Michael S. Briggs,W. H. Cleveland,Valerie Connaughton,Adam Goldstein,Andreas von Kienlin,Chryssa Kouveliotou,Bagrat Mailyan,Charles A. Meegan,William S. Paciesas,Arne Rau,Oliver J. Roberts,Péter Veres,Colleen A. Wilson-Hodge,Bin-Bin Zhang,Hendrik van Eerten +19 more
TL;DR: In this article, the gamma-ray bursts observed by the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-Ray Space Telescope (Fermi GBM) were analyzed with high spectral and temporal resolution.
Journal ArticleDOI
Gamma-ray bursts as cool synchrotron sources
TL;DR: In this paper, the authors performed time-resolved gamma-ray spectroscopy of single-peaked GRBs as measured with Fermi/GBM and demonstrated that idealized synchrotron emission, when properly incorporating time-dependent cooling of the electrons, is capable of fitting ~95% of all these GBM spectra.
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