Thursday, December 29, 2005

GRB - here we go again

GRB 051227 is looking very interesting

It is a hard GRB. Looks like it might be short as well, although there are weak delayed spikes and long low level emission tail.
Prompt followup has found a genuine faint red optical counterpart that seems associated with a rich cluster at redshift 0.7 and the OT is about 34 kpc in projection from a galaxy showing weak emission lines.

Combined with GRB051211 we're now seeing what seem to be moderate redshift short lived progenitors; it is tempting to say we are seeing two sub-classes of short GRBs, one set associated with NS-NS mergers and longish(???) lifetimes before merger, the other being shorter lived NS-BH mergers.

There are models now showing structure for tidal disruption of NS-BH mergers, I'd take those with a very large pinch of salt, the models are not fully relativistic, and this is a strong field regime. Resolution is also marginal to say anything sensible about return flow of marginally bound material and viscous evolution is purely artificial (and no B-fields!).

But looking very interesting indeed.


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