Everything everywhere all at once: A detailed study of GW230529

TL;DR

This paper analyzes the origin and physical characteristics of GW230529, combining population synthesis, numerical relativity, and nucleosynthesis models to understand its formation, properties, and observable signatures.

Contribution

It provides the first detailed study of GW230529's formation, final black hole parameters, and potential kilonova signals, integrating multiple modeling approaches.

Findings

Neutron star forms second in the binary system.

Black hole mass estimated at approximately 5.3 solar masses.

Kilonova ejecta mass ranges from 0 to 0.06 solar masses.

Abstract

This study investigates the origins of GW230529, delving into its formation from massive stars within isolated binary systems. Utilizing population synthesis models, we present compelling evidence that the neutron star component forms second. However, the event's low signal-to-noise ratio introduces complexities in identifying the underlying physical mechanisms driving its formation. Augmenting our analysis with insights from numerical relativity, we estimate the final black hole mass and spin to be approximately $5.3 M_\odot$ and $0.53$, respectively. Furthermore, we employ the obtained posterior samples to calculate the ejecta mass and kilonova light curves resulting from r-process nucleosynthesis. We find the ejecta mass to range within $0-0.06 M_{\odot}$, contingent on the neutron star equation of state. The peak brightness of the kilonovae light curves indicates that targeted follow-up observations with a Rubin-like observatory may have detected this emission.