Testing Dark Energy models vs $\Lambda$CDM Cosmology by Supernovae and Gamma Ray Bursts

TL;DR

This paper introduces a new method combining gamma-ray bursts and supernovae to better constrain dark energy models, especially at high redshift, and demonstrates their effectiveness in distinguishing these models from the standard $\\Lambda$CDM cosmology.

Contribution

It proposes a novel approach using combined GRB and SNeIa data with the Chevallier-Polarski-Linder parameterization to analyze dark energy's equation of state and transition phase.

Findings

GRBs calibrated by SNeIa are effective high-redshift distance indicators.

Combined GRB and SNeIa data reveal a slope change around redshift z~0.5.

The results support the acceleration signature observed in the universe.

Abstract

A new method to constrain the cosmological equation of state is proposed by using combined samples of gamma-ray bursts (GRBs) and supernovae (SNeIa). The Chevallier-Polarski-Linder parameterization is adopted for the equation of state in order to find out a realistic approach to achieve the deceleration/acceleration transition phase of dark energy models. As results, we find that GRBs, calibrated by SNeIa, could be, at least, good distance indicators capable of discriminating cosmological models with respect to $\Lambda$CDM at high redshift. Besides, GRBs+SNeIa combined redshift-distance diagram puts better in evidence the change of slope around redshift $z\sim 0.5$ which is usually addressed as the "signature" of today observed acceleration. This feature could be interpreted, in more standard way, by the red sequence in galaxy clusters.