A close correlation between the spectral lags and redshifts of gamma-ray bursts

Abstract

Based on nine BATSE GRBs with known redshifts, we found that the maximum spectral lag of all the pulses in a gamma-ray burst (GRB) appears to be anti-correlated with the redshift of the burst. In order to confirm this finding, we analyzed 10 GRBs detected by HETE-2 with known redshifts and found a similar relation. Using the relation, we estimated the redshifts of 878 long GRBs in the BATSE catalog, then we investigated the distributions of the redshifts and 869 E(iso), of these GRBs. The distribution of the estimated redshifts is concentrated at z = 1.4 and the distribution of E(iso) peaks at 10(52.5) erg. The underlying physics of the correlation is unclear at present.