geminiann07004 — Announcement
Are Short Gamma-ray Bursts Cosmic Tricksters?
18 April 2007: Analysis of nine short gamma-ray bursts (GRBs) observed with Gemini, Magellan, and the Hubble Space Telescope reveals that the progenitors of these GRBs may reside in faint host galaxies at redshifts of z = 1.1 and beyond (geminiann07004a). Unexpectedly, the host galaxies of these short GRBs (with R ~ 23-27 mag) can be more than a 100 times fainter than those of previously known short GRBs (brighter than R ~ 22 mag) (geminiann07004b). Therefore the hosts of the recently observed short GRBs are starkly different from the first few short GRBs hosts, which were all at z < 0.5. It seems that our understanding of the nature of GRB progenitors may be undergoing a paradigm shift. Although initial observations suggested that short GRBs occur at significantly lower redshifts than long GRBs (which occur at z ~ 3), the recent observations establish for the first time that a third or more …