Constraining the PopIII IMF with high-z GRBs

Understand

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.