Pair-instability mass loss for top-down compact object mass calculations

TL;DR

This paper introduces a top-down approach to calculating compact object masses by directly removing mass based on physical mechanisms, improving the continuity and accuracy of mass distributions used in gravitational-wave analysis.

Contribution

It proposes a novel top-down remnant mass prescription that incorporates mass-loss mechanisms, including pulsational-pair instability, ensuring more realistic and continuous mass distributions.

Findings

The new prescription recovers existing mass models at low masses.

It ensures continuity across different supernova regimes.

The approach can be extended to other mass-loss mechanisms.

Abstract

Population synthesis relies on semi-analytic formulae to determine masses of compact objects from the (helium or carbon-oxygen) cores of collapsing stars. Such formulae are combined across mass ranges that span different explosion mechanisms, potentially introducing artificial features in the compact object mass distribution. Such artifacts impair the interpretation of gravitational-wave observations. We propose a "top-down" remnant mass prescription where we remove mass from the star for each possible mass-loss mechanism, instead of relying on the fallback onto a "proto-compact-object" to get the final mass. For one of these mass-loss mechanisms, we fit the metallicity-dependent mass lost to pulsational-pair instability supernovae from numerical simulations. By imposing no mass loss in the absence of pulses, our approach recovers the existing compact object masses prescription at the low mass end and ensures continuity across the core-collapse/pulsational-pair-instability regime. Our remnant mass prescription can be extended to include other mass-loss mechanisms at the final collapse.