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GRB980923. A burst with a short duration high-energy component

Gonzalez, M. M. and Sacahui, J. R. and Ramirez, J. L. and Patricelli, B. and Kaneko Göğüş, Yuki (2012) GRB980923. A burst with a short duration high-energy component. Astrophysical Journal, 755 (2). ISSN 0004-637X (Print) 1538-4357 (Online)

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Official URL: http://dx.doi.org/10.1088/0004-637X/755/2/140

Abstract

The prompt emission of gamma-ray bursts (GRBs) is usually well described by the Band function: two power laws (PLs) joined smoothly at a given break energy. In addition to the Band component, a few bursts (GRB941017, GRB090510, GRB090902B, and GRB090926A) show clear evidence of a distinct high-energy spectral component, which in some cases evolves independently from the prompt keV component and is well described by a PL, sometimes with a cutoff energy; this component is found to have long duration, even longer than the burst itself for all four bursts. Here we report the observation of an anomalous short duration high-energy component in GRB980923. GRB980923 is one of the brightest GRBs observed by BATSE. Its light curve is characterized by a rapid variability phase lasting similar to 40 s, followed by a smooth emission tail lasting similar to 400 s. A detailed joint analysis of BATSE (Large Area Detector and Spectroscopy Detector) and EGRET TASC data of GRB980923 reveals the presence of an anomalous keV to MeV component in the spectrum that evolves independently from the prompt keV one. This component is well described by a PL with a spectral index of -1.44 and lasts only similar to 2 s; it represents one of the three clearly separated spectral components identified in GRB980923, the other two being the keV prompt emission, well described by the Band function and the tail, well fit by a Smoothly Broken Power Law.

Item Type:Article
Additional Information:Article Number: 140
Uncontrolled Keywords:acceleration of particles; astroparticle physics; gamma-ray burst: general; gamma-ray burst: individual: GRB980923; radiation mechanisms: non-thermal
Subjects:Q Science > QB Astronomy > QB460-466 Astrophysics
Q Science > QB Astronomy
ID Code:20930
Deposited By:Yuki Kaneko Göğüş
Deposited On:26 Nov 2012 15:40
Last Modified:26 Nov 2012 15:40

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