Constraining the PopIII IMF with high-z GRBs

TL;DR

This study uses advanced simulations to explore how high-redshift gamma-ray bursts can reveal signatures of the first stars' initial mass functions, helping to constrain early universe star formation models.

Contribution

It introduces a comprehensive simulation framework that models PopIII and PopII star formation and metal enrichment, providing new methods to interpret high-redshift GRB observations.

Findings

PopIII-dominated GRB hosts are model independent.

Abundance ratios can distinguish massive from intermediate PopIII stars.

Properties of PopIII-dominated GRB hosts are insensitive to first star mass assumptions.

Abstract

We study the possibility to detect and distinguish signatures of enrichment from PopIII stars in observations of PopII GRBs (GRBIIs) at high redshift by using numerical N-body/hydrodynamical simulations including atomic and molecular cooling, star formation and metal spreading from stellar populations with different initial mass functions (IMFs), yields and lifetimes. PopIII and PopII star formation regimes are followed simultaneously and both a top-heavy and a Salpeter-like IMF for pristine PopIII star formation are adopted. We find that the fraction of GRBIIs hosted in a medium previously enriched by PopIII stars (PopIII-dominated) is model independent. Typical abundance ratios, such as [Si/O] vs [C/O] and [Fe/C] vs [Si/C], can help to disentangle enrichment from massive and intermediate PopIII stars, while low-mass first stars are degenerate with regular PopII generations. The properties of galaxies hosting PopIII-dominated GRBIIs are not very sensitive to the particular assumption on the mass of the first stars.