The Gamma Ray Bursts Hubble diagram

TL;DR

This paper explores calibrating Gamma Ray Bursts as standard candles to extend the Hubble diagram into earlier cosmic epochs, analyzing different calibration methods and potential systematic biases.

Contribution

It introduces and compares three calibration methods for GRBs using cosmological models, cosmography, and local regression, assessing their impact on the Hubble diagram.

Findings

Calibration methods show no significant dependence on the chosen approach.

No substantial evolution of calibration parameters with redshift detected.

Systematic effects from calibration and sample homogeneity are minimal.

Abstract

Thanks to their enormous energy release, Gamma Rays Bursts (GRBs) have recently attracted a lot of interest to probe the Hubble diagram (HD) deep into the matter dominated era and hence complement Type Ia Supernovae (SNeIa). We consider here three different calibration methods based on the use of a fiducial LCDM model, on cosmographic parameters and on the local regression on SNeIa to calibrate the scaling relations proposed as an equivalent to the Phillips law to standardize GRBs finding any significant dependence. We then investigate the evolution of these parameters with the redshift to obtain any statistical improvement. Under this assumption, we then consider possible systematics effects on the HDs introduced by the calibration method, the averaging procedure and the homogeneity of the sample arguing against any significant bias.