Gamma ray burst distances and the timescape cosmology

TL;DR

This paper evaluates gamma ray bursts as distance indicators to differentiate between the timescape and CDM cosmological models at high redshifts, finding slight preference for the timescape model but noting uncertainties.

Contribution

It applies GRB data to test the timescape cosmology against CDM, extending the analysis to redshifts around 7.

Findings

Timescape model fits GRB data slightly better than CDM.

Systematic uncertainties prevent definitive model discrimination.

GRBs can potentially extend the Hubble diagram to higher redshifts.

Abstract

Gamma ray bursts can potentially be used as distance indicators, providing the possibility of extending the Hubble diagram to redshifts ~7. Here we follow the analysis of Schaefer (2007), with the aim of distinguishing the timescape cosmological model from the \LambdaCDM model by means of the additional leverage provided by GRBs in the range 2 < z < 7. We find that the timescape model fits the GRB sample slightly better than the \LambdaCDM model, but that the systematic uncertainties are still too little understood to distinguish the models.