Don Lamb: Short GRBs

EUD seminar by Don Lamb. He summarized the story from last year on short GRBs then talked extensively about a HETE burst that appears short but has a photometric redshift of 1.5 (if heavily reddened) or 4.6. He suggested that there are problems with a classification scheme based on spectral hardness since results appear not to be consistent between different missions. The T90 classification also has issues because it is measured in the observed frame. If long GRBs are cosmological then the rest frame durations are much shorter (by 1+z) so the distinction between short and long is eroded. Finally he noted that the presence of a spectral lag is a good classifier of a long GRB but there are some short bursts with negligible lag but large error bars implying they are not highly structured (so lag cannot be well-measured) so these might actually be similar to long bursts.

Keywords: GRB