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

TL;DR

This study performs a joint spectral and temporal analysis of gamma-ray bursts detected simultaneously by Swift/BAT and Fermi/GBM, confirming known correlations and exploring differences in duration measurements across energy bands.

Contribution

It provides the first combined spectral and temporal analysis of joint Swift/BAT and Fermi/GBM GRB data, confirming correlations and highlighting energy-dependent duration differences.

Findings

Confirmed correlation between BAT photon index and Epeak.

Validated the E_gamma,iso - Epeak,rest relation with larger scatter.

Found energy-dependent differences in T_90 durations for long and short GRBs.

Abstract

Using the gamma-ray bursts simultaneously detected by Swift/BAT and Fermi/GBM we performed a joint spectral and temporal analysis of the prompt emission data and confirm the rough correlation between the BAT-band photon index Gamma_BAT and the peak spectral energy Epeak. With the redshift known sub-sample, we derived the isotropic gamma-ray energy E_gamma,iso and also confirm the E_gamma,iso - Epeak,rest relation, with a larger scatter than the Amati sample but consistent with GBM team analyses. We also compare the T_90 values derived in the GBM band with those derived in the BAT band and find that for long GRBs the BAT T_90 is usually longer than the GBM T_90, 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.