Study of luminosity and time evolution in X-ray afterglows of GRBs

TL;DR

This study analyzes the luminosity and duration of X-ray afterglows in GRBs, updating previous correlations with a larger dataset and accounting for cosmological evolution to understand their intrinsic relationship.

Contribution

It provides an updated analysis of the luminosity-time correlation in GRB X-ray afterglows using a larger sample and applies the Efron-Petrosian method to correct for redshift evolution effects.

Findings

Confirmed anti-correlation between plateau end time and luminosity.

Quantified intrinsic correlation after correcting for cosmological evolution.

Expanded dataset improves statistical significance of the correlation.

Abstract

Gamma-ray bursts (GRBs), which have been observed up to redshifts $z \approx 9.5$ can be good probes of the early universe and have the potential of testing cosmological models. The analysis by Dainotti of GRB Swift afterglow lightcurves with known redshifts and definite X-ray plateau shows an anti-correlation between the \underline{rest frame} time when the plateau ends (the plateau end time) and the calculated luminosity at that time (or approximately an anti-correlation between plateau duration and luminosity). We present here an update of this correlation with a larger data sample of 101 GRBs with good lightcurves. Since some of this correlation could result from the redshift dependences of these intrinsic parameters, namely their cosmological evolution we use the Efron-Petrosian method to estimate the luminosity and time evolution and to correct for this effects to determine the intrinsic nature of this correlation.