EDP Sciences
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Volume 420, Number 2, June III 2004
Page(s) 501 - 505
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20041344

A&A 420, 501-505 (2004)
DOI: 10.1051/0004-6361:20041344

The Compton trail of gamma-ray bursts: A long-after glow

D. Allard and E. Parizot

Institut de Physique Nucléaire d'Orsay, 15 rue Clémenceau, 91406 Orsay Cedex, France

(Received 28 January 2004 / Accepted 16 March 2004)

As they travel through the gas of the host galaxy, some of the gamma-rays emitted in a Gamma-Ray Burst (GRB) may experience Compton scattering and reach an observer even if he is not located in the direction of the primary photon beam. Such a process will last until the GRB photons have left their host galaxy, and the ambient electron density becomes negligible. We investigate the observability of this indirect GRB light, which would be seen as a faint trail along the path of the GRB photons, long after the initial event. We find that the so-called Compton trail of a 1051 erg GRB can easily be observed from Earth, wherever the explosion occurred in our Galaxy in the past few thousand years. Gamma-ray surveys of the Galaxy can therefore provide constraints on the true GRB rate (or number of GRBs per supernova), independently of the GRB beaming angle. We also calculate the expected light curve and shape of the emitting region as a function of time.

Key words: gamma rays: bursts -- gamma rays: theory -- gamma rays: observations

Offprint request: E. Parizot, parizot@ipno.in2p3.fr

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