Title:              Gravitational lensing origin for a possible
                    gamma-ray burst repeater?
Authors:            HANLON, L.O.; HERMSEN, W.; KIPPEN, R.M.; MATZ, S.M.;
                    O'FLAHERTY, K.S.; PREECE, R.D.; RYAN, J.;
                    SCHOENFELDER, V.; WILLIAMS, O.R.; WINKLER, C.
Journal:            Astronomy and Astrophysics, v.296, p.41
Publication Date:   04/1995
Origin:             A&A via CDS
A&A Keywords:       GAMMA-RAYS: BURSTS
Abstract Copyright: (c) 1995: Astronomy & Astrophysics
Bibliographic Code: 1995A&A...296L..41H

Abstract

One observational consequence of a cosmological distribution of {gamma}-ray
bursts is that some recurrent bursts, due to gravitational lensing, should
be seen during the life time of the Compton Gamma-Ray Observatory. These
would be identifiable by their spatial coincidence and by their identical
time profiles and spectra. The COMPTEL experiment, on board the Compton
Gamma-Ray Observatory, has imaged two {gamma}-ray bursts(GRB 930704 and GRB
940301) with coincident locations, separated in time by eight months. We
report here on the spectral andtemporal analysis of these two events in
order to establish whether they are gravitationally lensed images of the
same burst. We conclude that although the envelopes of the time profiles are
similar, they are sufficiently different on short time scales to rule out
the standard lensing hypothesis. Furthermore, spectral dissimilarities
between the pair mitigate against the possibility that the differences in
time profiles could have arisen through microlensing. Since lensing is ruled
out, the remaining possibilities are an accidental coincidence of unrelated
bursts or a true repeating burst source. The latter would severely constrain
cosmological burst models.

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