GCN Circular 2942
Subject
SGR 1806-20 and extragalactic short-duration GRBs
Date
2005-01-07T16:31:10Z (19 years ago)
From
Arnon Dar at Technion-Israel Inst. of Tech <arnon@physics.technion.ac.il>
If the giant short peak of the giant flare from SGR 1900+14 on 27/12/2004
(GCN 2920, GCN 2923, GCN 2936, GCN2927) at an estimated distance of
15 kpc (Corbel and Eikenberg A\&A 419, 191, 2004) could have been seen by
BATSE as a hard, short-duration GRB up to a distance of 80 Mpc (GCN 2936),
then SGRs in external galaxies can be the main source of the hard,
short-duration GRBs seen by BATSE: The local optical luminosity within
a distance of 80 Mpc is about 10^4 times the Milky Way [MW] luminosity,
(\rho_L=1.84 10^8 h L[sun] Mpc^{-3}; L[MW]=2.4 10^{10} L[sun], where,
h=0.65, is the Hubble constant in units of 100 km/s/Mpc). If the observed
rate from Earth of such bursts per Milky Way luminosity is \sim 1 in 15
years (one since the launch of CGRO), it yields, before correcting for
triggering efficiency and for sky solid angle coverage, an observable
rate by BATSE of about 2 hard, short-duration, cosmic GRBs per day,
independent of the beaming angle.