Hyperstars – Main Origin of Short Gamma-Ray Bursts?

Abstract

Short-duration hard-spectrum gamma ray bursts (SHBs) such as 050509B, 050709, 050724 and 050813 could have been the narrowly beamed initial spike of hyperflares of soft gamma ray repeaters (SGRs) in 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.