A Study of Cosmological Models Based on Long Gamma-ray Bursts Duration Histogram

TL;DR

This study analyzes gamma-ray burst durations to compare cosmological models, finding that the ωCDM model is statistically favored over the ΛCDM model based on Monte Carlo simulations and histogram analysis.

Contribution

It introduces a novel method of using GRB duration histograms to evaluate and compare cosmological models, specifically favoring the ωCDM model over ΛCDM.

Findings

ωCDM model is statistically favored over ΛCDM.

The dark energy equation of state parameter α is approximately 0.08.

GRB duration data supports a non-zero α in dark energy models.

Abstract

The duration of more than one thousand gamma-ray bursts (GRBs) has been measured by Swift satellite. Besides the redshift distribution of GRBs, the burst duration could be another significant property of GRBs that can be analyzed. In this project, First, we find the detection rate of Swift/BAT for a cosmological model with the $ \omega CDM$ model, then by performing a Monte-Carlo simulation, we find the "long" GRB duration histogram to compare the cosmological model with the $ \omega CDM$ model and the $\Lambda CDM$ model. The $\chi^2$ minimization method is employed to determine the optimal value of $\alpha$ in the dark energy equation of state, $P= c \omega(z) \rho$, with $\omega(z)=1+\alpha z$ as $\alpha=0.08 ^{+ 0.04}_{-0.02}$. We showed that the $\omega CDM$ model is statistically favored over the $\Lambda CDM$ model. Other studies by measuring the expansion rate of the Universe directly from the SNIa data by Pantheon and DES-SN3YR samples and the combinations of SNIa, CMB, and BAO data confirmed that the value of $\alpha$ in the dark energy equation of state is not zero \citep{Dark_energy_Abbott, 2011Beutler, 2014Anderson, 2015Ross, 2016PlanckCollaboration, Alam2017, Mazumdar2021}.