Correlations between Event Rates of Short Gamma-Ray Bursts and Star Formation Rates with/without Time Delay

TL;DR

This study analyzes the distributions and rates of short Gamma-Ray Bursts (SGRBs) from different detectors, revealing correlations with star formation rates and suggesting a link to old star populations or binary mergers.

Contribution

It provides a comprehensive comparison of SGRB properties across multiple detectors and explores their connection to star formation histories with/without time delays.

Findings

Fermi and Konus-wind SGRBs have identical redshift and luminosity distributions.

Swift SGRBs have lower median luminosity and higher local event rates.

SGRB rates align with star formation rates but decline steeply at low redshift.

Abstract

In this paper, we systematically investigate the redshift and luminosity distributions as well as the event rates of short Gamma-Ray Bursts (SGRBs) detected by Swift, Fermi, Konus-wind satellites. It is found that the distributions of redshift and luminosity of Fermi and Konus-wind SGRBs are identical and they obviously differ from those of Swift/BAT SGRBs. The luminosity distributions of SGRBs detected by diverse detectors can be uniformly fitted by a smoothly broken power-law function. The median luminosity of Swift SGRBs is about one order of magnitude smaller than that of Fermi/GBM or Konus-wind SGRBs. We also compare the local event rates of Swift/BAT, Fermi/GBM and Konus-wind SGRBs and find that the local rate of Swift SGRBs is around two orders of magnitude larger than that of either Fermi or Konus-wind SGRBs, while the latter two rates are comparable. The observed SGRB rates can be successfully fitted by a power-law plus Gauss function. The SGRB rates of three kinds of detectors matches the delayed/undelayed SFRs well except the delayed Lognormal and/or Gaussian SFRs at higher redshift and exceed all types of SFRs at lower redshift of $z<1$. After deducting the diverse SFR components from the SGRB rates, we surprisingly notice that the remaining SGRB rates steeply decline with redshift in a power-law-like form, indicating that these SGRBs could emerge from the old star populations or compact binary star mergers.