Asymmetric subpeaks of short duration bursts
Varsha Gupta, Patrick Das Gupta
P. N. Bhat
Subpeaks in 65 short duration bursts belonging to the
3B catalogue have been identified and are fitted with
lognormal functions as most subpeaks are of FRED kind.
Characterising the symmetry of a subpeak
by the ratio of rise to decay time, we find that statistically
the first subpeak of a burst tends to be more asymmetric than
the subsequent ones. If the FRED nature exhibited by the
subpeaks in GRBs is due to relativistic beaming then one may
obtain an estimate of the fire-ball shell `speed' associated
with a subpeak using the latter's rise time and width. Our
analysis shows that the `speed' associated with the first
subpeak statistically tends to be larger than that for the
subsequent peaks. In this work, we have also studied
correlations between various parameters like hardness ratio,
rapidity index etc. that characterise a burst.
File translated from TEX by TTH, version 2.32.
On 16 Jul 1999, 09:19.