Cosmology with Gamma Ray Bursts

TL;DR

This paper explores the potential of Gamma-Ray Bursts as standard candles for cosmology by analyzing their collimation-corrected energies and correlations, enabling high-redshift universe probing and insights into cosmic acceleration.

Contribution

It demonstrates that GRBs can be used as reliable cosmological tools through a new correlation between their energetics and emission frequency, improving distance measurements.

Findings

Collimation-corrected energy correlates with emission frequency.

GRBs can probe the universe at high redshifts.

Results support GRBs as complementary to supernovae for cosmology.

Abstract

Apparently, Gamma-Ray Bursts (GRBs) are all but standard candles. Their emission is collimated into a cone and the received flux depends on the cone aperture angle. Fortunately we can derive the aperture angle through an achromatic steepening of the lightcurve of the afterglow, and thus we can measure the "true" energetics of the prompt emission. Ghirlanda et al. (2004) found that this collimation-corrected energy correlates tightly with thefrequency at which most of the radiation of the prompt is emitted. Through this correlation we can infer the burst energy accurately enough for a cosmological use. Using the best known 15 GRBs we find very encouraging results that emphasize the cosmological GRB role. Probing the universe with high accuracy up to high redshifts, GRBs establish a new insight on the cosmic expanding acceleration history and accomplish the role of "missing link" between the Cosmic Microwave Background and type Ia supernovae, motivating the most optimistic hopes for what can be obtained from the bursts detected by SWIFT.