Constraints on $w_0$ and $w_a$ of Dark Energy from High Redshift Gamma Ray Bursts

TL;DR

This paper uses high-redshift gamma-ray bursts to extend the Hubble diagram and constrain dark energy parameters, showing consistency with the standard model and potential for improved future constraints.

Contribution

It extends the cosmological analysis to higher redshifts using GRBs and forecasts improved dark energy constraints with future observations.

Findings

Current GRB data are consistent with the standard cosmological model.

GRBs can enhance dark energy constraints beyond supernovae due to higher redshifts.

Future GRB observations could significantly tighten dark energy parameter estimates.

Abstract

We extend the Hubble diagram up to $z = 5.6$ using 63 gamma-ray bursts (GRBs) via peak energy-peak luminosity relation (so called Yonetoku relation), and obtain constraints on cosmological parameters including dynamical dark energy parametrized by $P/\rho\equiv w(z) = w_0 + w_a \cdot z/(1+z)$. It is found that the current GRB data are consistent with the concordance model, ($\Omega_m = 0.28, \Omega_{\Lambda} = 0.72, w_0 = -1, w_a = 0$), within two sigma level. Although constraints from GRBs themselves are not so strong, they can improve the conventional constraints from SNeIa because GRBs have much higher redshifts. Further we estimate the constraints on the dark-energy parameters expected by future observations with GLAST (Gamma-ray Large Area Space Telescope) and \swift by Monte-Carlo simulation. Constraints would improve substantially with another 150 GRBs.