Guetta 2010 长暴GeV辐射对伽马暴的限制

主要内容:
高能GeV的观测发现没有想象的多，这给高能辐射一个限制，至少大部分暴不是由高能辐射主导，也说明MeV的高能部分不是一个幂律延伸到GeV。如果这个没有高能辐射来自于GeV光子的广深的话，对Lorentz因子也给出了限制小于300.

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Title:		FERMI constraints on the high energy, ~1 GeV, emission of long GRBs
Authors:		Guetta, Dafne; Pian, Elena; Waxman, Eli
Publication:		eprint arXiv:1003.0566
Publication Date:		03/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		9 pages, 6 figures. Submitted to A&A
Bibliographic Code:		2010arXiv1003.0566G

Abstract

We investigate the constraints imposed on the luminosity function (LF) of long duration Gamma Ray Bursts (LGRBs) by the flux distribution of bursts detected by the GBM at ~1 MeV, and the implications of the non detection of the vast majority, ~95%, of the LGRBs at higher energy, ~1 GeV, by the LAT detector. We find a LF that is consistent with those determined by BATSE and Swift. The non detections by LAT set upper limits on the ratio R of the prompt fluence at ~1 GeV to that at ~1 MeV. The upper limits are more stringent for brighter bursts, with R<{0.1,0.3,1} for {5,30,60}% of the bursts. This implies that for most bursts the prompt ~1 GeV emission may be comparable to the ~1 MeV emission, but can not dominate it. The value of R is not universal, with a spread of (at least) an order of magnitude around R~10^(-1). For several bright bursts with reliable determination of the photon spectral index at ~1 MeV, the LAT non detection implies an upper limit to the ~100 MeV flux which is 0.1

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