Using the COSMIC Population Synthesis Code to Investigate How Metallicity Affects the Rates of Interacting Binaries

TL;DR

This study uses the COSMIC population synthesis code to analyze how metallicity influences the formation rates of massive star systems with compact companions, which are potential progenitors of long gamma-ray bursts, revealing a strong anti-correlation.

Contribution

The paper introduces a detailed analysis of metallicity effects on the formation rates of specific binary systems using the COSMIC code, providing new insights into their evolution and cosmic occurrence.

Findings

Formation rates are anti-correlated with metallicity.

Systems are about 10 times more frequent at certain low metallicities.

Results inform predictions of gamma-ray burst progenitors over cosmic time.

Abstract

We use COSMIC, a galaxy population synthesis code, to investigate how metallicity affects the rate of formation of massive stars with a closely orbiting compact object companion, the suggested progenitors of radio loud long gamma-ray bursts. We present the evolution time of these systems at different metallicities, and how the formation rates of these systems are anti-correlated with metallicity. In particular, these systems occur about 10 times more frequently in at metallicities between $Z = 2\times 10^{-4}$ and $2 \times 10^{-3}$, compared to those between $Z = 2\times 10^{-3}$ and $2 \times 10^{-2}$. This work serves as a prerequisite to predicting the global rates of these systems as a function of redshift, ultimately giving crucial insight into our understanding of the progenitors of long gamma-ray bursts and their evolution over cosmic time.