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

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.