Spectral and temporal analysis of the joint Swift/BAT-Fermi/GBM GRB sample

Abstract

Using the gamma-ray bursts (GRBs) simultaneously detected by Swift/Burst Alert Telescope (BAT) and Fermi/Gamma-ray Burst Monitor (GBM), we performed a joint spectral and temporal analysis of the prompt emission data and confirmed the rough correlation between the BAT-band photon index Γ^BAT and the peak spectral energy E<inf>peak</inf>. With the redshift-known subsample, we derived the isotropic gamma-ray energy E<inf>γ, iso</inf> and also confirmed the E<inf>γ,iso</inf> - E<inf>peak,rest</inf> relation, with a larger scatter than the Amati sample but consistent with GBM team analyses. We also compare the T<inf>90</inf> values derived in the GBM band with those derived in the BAT band and find that for long GRBs the BAT T<inf>90</inf> is usually longer than the GBM T<inf>90</inf>, while for short GRBs the trend reverses. This is consistent with the soft/hard nature of long/short GRBs and suggests the importance of an energy-dependent temporal analysis of GRBs. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.