The peak flux distribution of bright gamma-ray bursts measured with ULYSSES

¹ Centre d'Étude Spatiale des Rayonnements, CNRS/UPS, BP. 4346, 31028 Toulouse Cedex 4, France
² University of California at Berkeley, Space Sciences Laboratory, Berkeley, CA 94720-7450, U.S.A.

Send offprint request to: J-L. Atteia

Received: 21 January 1999
Accepted: 28 May 1999

Abstract

Observations of gamma-ray burst afterglows have shown that these events come from formidable explosions at cosmological distances. If the most distant GRBs seen by BATSE have redshifts of the order of 3-6 (e.g. GB 971214), it is a coincidence that the bright end of the GRB intensity distribution displays the slope expected for a Euclidean distribution of sources. We analyze nearly 10 years of continuous observation of bright GRBs with ULYSSES, in order to constrain their intensity distribution. This extensive dataset (more than 200 bursts in the "Euclidean” part of the curve) is used to quantify the agreement of the data with the canonical slope of .