Comparing the spectral lag of short and long gammaray bursts and its relation with the luminosity
Abstract
We investigated the restframe spectral lags of two complete samples of bright long (50) and short (6) gammaray bursts (GRB) detected by Swift. We analysed the Swift/Burst Alert Telescope data through a discrete crosscorrelation function fitted with an asymmetric Gaussian function to estimate the lag and the associated uncertainty. We find that half of the long GRBs have a positive lag and half a lag consistent with zero. All short GRBs have lags consistent with zero. The distributions of the spectral lags for short and long GRBs have different average values. Limited by the small number of short GRBs, we cannot exclude at more than 2σ significance level that the two distributions of lags are drawn from the same parent population. If we consider the entire sample of long GRBs, we do not find evidence for a lagluminosity correlation, rather the lagluminosity plane appears filled on the lefthand side, thus suggesting that the lagluminosity correlation could be a boundary. Short GRBs are consistent with the long ones in the lagluminosity plane.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 January 2015
 DOI:
 10.1093/mnras/stu2153
 arXiv:
 arXiv:1410.5216
 Bibcode:
 2015MNRAS.446.1129B
 Keywords:

 gammaray burst: general;
 Astrophysics  High Energy Astrophysical Phenomena
 EPrint:
 11 pages, 6 figures, 2 tables, accepted for publication in MNRAS