The star formation history inferred from long gamma-ray bursts with high pseudo-redshifts

TL;DR

This paper models the star formation history using high pseudo-redshift gamma-ray bursts, suggesting a significant presence of Pop III GRBs and estimating their detectability with current instruments.

Contribution

It introduces a semi-analytical model linking Pop I/II and III star formation rates to GRB distributions, providing new insights into early universe star formation.

Findings

A considerable number of Pop III GRBs may exist in current Swift data.

Only about 0.6% of Pop III GRBs could trigger Swift BAT.

Results inform future detection prospects of Pop III stars.

Abstract

By employing a simple semi-analytical star formation model where the formation rates of Population (Pop) I/II and III stars can be calculated, respectively, we account for the number distribution of gamma-ray bursts (GRBs) with high pseudo-redshifts that was derived from an empirical luminosity-indictor relationship. It is suggested that a considerable number of Pop III GRBs could exist in the present sample of Swift GRBs. By further combining the implication for the star formation history from the optical depth of the CMB photons, it is also suggested that only a very small fraction 0.6% of Pop III GRBs could have triggered the Swift BAT. These results could provide an useful basis for estimating future detectability of Pop III stars and their produced transient phenomena.