Gamma-ray burst contributions to constraining the evolution of dark energy

TL;DR

This paper assesses how gamma-ray bursts can help constrain dark energy's properties at various redshifts, finding they are more effective at middle redshifts than at higher ones without improved luminosity relations.

Contribution

It provides a quantitative analysis of GRBs' potential in constraining dark energy evolution and highlights the need for better luminosity relations for high-redshift GRBs.

Findings

GRBs can constrain dark energy at middle redshifts similarly to SNe Ia.

Constraining dark energy beyond SNe Ia redshifts with GRBs is challenging without new luminosity relations.

Number of GRBs needed for substantial high-redshift constraints is estimated.

Abstract

We explore the gamma-ray bursts' (GRBs') contributions in constraining the dark energy equation of state (EOS) at high ($1.8 < z < 7$) and at middle redshifts ($0.5 < z < 1.8$) and estimate how many GRBs are needed to get substantial constraints at high redshifts. We estimate the constraints with mock GRBs and mock type Ia supernovae (SNe Ia) for comparisons. When constraining the dark energy EOS in a certain redshift range, we allow the dark energy EOS parameter to vary only in that redshift bin and fix EOS parameters elsewhere to -1. We find that it is difficult to constrain the dark energy EOS beyond the redshifts of SNe Ia with GRBs unless some new luminosity relations for GRBs with smaller scatters are discovered. However, at middle redshifts, GRBs have comparable contributions with SNe Ia in constraining the dark energy EOS.