Single star progenitors of long gamma-ray bursts I: Model grids and redshift dependent GRB rate

TL;DR

This paper models the evolution of massive stars at various metallicities to predict which can produce long gamma-ray bursts, analyzing their expected rates across different redshifts based on stellar physics and empirical data.

Contribution

It provides detailed stellar evolution model grids considering rotation and metallicity, linking these to long GRB progenitors and their redshift-dependent occurrence rates.

Findings

GRB production is limited to metallicities Z \\lsim 0.004.

Approximately 50% of GRBs are predicted to occur at redshifts above z=4.

The global GRB to supernova ratio is about 1/200.

Abstract

We present grids of massive star evolution models at four different metallicities (Z=0.004, 0.002, 0.001, 0.00001). The effects of rotation on the stellar structure and the transport of angular momentum and chemical elements through the Spruit-Tayler dynamo and rotationally induced instabilities are considered. After discussing uncertainties involved with the adopted physics, we elaborate the final fate of massive stars as a function of initial mass and spin rate, at each considered metallicity. In particular, we investigate for which initial conditions long gamma-ray bursts (GRBs) are expected to be produced in the frame of the collapsar model. Then, using an empirical spin distribution of young massive metal-poor stars and a specified metallicity-dependent history of star-formation, we compute the expected GRB rate as function of metallicity and redshift based on our stellar evolution models. The GRB production in our models is limited to metallicities of Z \lsim 0.004, with the consequence that about 50 % of all GRBs are predicted to be found at redshifts above z = 4, with most supernovae occurring at redshifts below z\simeq 2.2. The average GRB/SN ratio predicted by our model is about 1/200 globally, and 1/1250 at low redshift. Future strategies for testing the considered GRB progenitor scenario are briefly discussed.