Cosmology with Gamma-Ray Bursts

TL;DR

Gamma-Ray Bursts are extremely luminous cosmic events that can serve as probes for understanding the universe's composition, expansion, and early star formation, through their spectral properties and high-redshift observations.

Contribution

The paper updates the analysis of GRB correlations to constrain cosmological parameters and discusses future prospects for using GRBs in high-redshift cosmology and intergalactic medium studies.

Findings

Updated analysis of 95 GRBs constrains Omega_M.

GRBs can potentially probe the universe's dark ages.

Discussion of GRBs for high-resolution IGM spectroscopy.

Abstract

Gamma-Ray Bursts (GRBs) are the brightest sources in the universe, emit mostly in the hard X-ray energy band and have been detected at redshifts up to ~8.1. Thus, they are in principle very powerful probes for cosmology. I shortly review the researches aimed to use GRBs for the measurement of cosmological parameters, which are mainly based on the correlation between spectral peak photon energy and total radiated energy or luminosity. In particular, based on an enriched sample of 95 GRBs, I will provide an update of the analysis by Amati et al. (2008) aimed at extracting information on Omega_M and, to a less extent, on Omega_Lambda, from the Ep,i - Eiso correlation. I also briefly discuss the perspectives of using GRBs as cosmological beacons for high resolution absorption spectroscopy of the IGM (e.g., WHIM), and as tracers of the SFR, up to the "dark ages" (z > 6) of the universe.