Hyperstars - Main Origin of Short Gamma Ray Bursts?

Abstract

The first well-localized short-duration gamma ray bursts (GRBs), GRB 050509b, GRB 050709 and GRB 050724, could have been the narrowly beamed initial spike of a burst/hyper flare of soft gamma ray repeaters (SGRs) in host galaxies at cosmological distances. Such bursts are expected if SGRs are young hyperstars, i.e. neutron stars where a considerable fraction of their neutrons have converted to hyperons and/or strange quark matter.Comment: Invited talk to be published in the proceedings of the intl. Workshop `High Energy Cosmic Sources' May 23-28, 2005, Vulcano, Italy 200