Remnant baryon mass outside of the black hole after a neutron star-black hole merger

TL;DR

This paper introduces a new formula to predict the remnant baryon mass outside a black hole after a neutron star-black hole merger, validated with simulations, aiding in distinguishing merger types and understanding source physics.

Contribution

A simple, validated formula that accurately predicts post-merger remnant mass, including regimes with comparable masses and high black hole spins, improving previous models.

Findings

Formula validated with 75 simulations.

Improves predictions for high-spin and comparable-mass mergers.

Helps differentiate NSNS from NSBH mergers.

Abstract

Gravitational-wave (GW) and electromagnetic (EM) signals from the merger of a Neutron Star (NS) and a Black Hole (BH) are a highly anticipated discovery in extreme gravity, nuclear-, and astrophysics. We develop a simple formula that distinguishes between merger outcomes and predicts the post-merger remnant mass, validated with 75 simulations. Our formula improves on existing results by describing critical unexplored regimes: comparable masses and higher BH spins. These are important to differentiate NSNS from NSBH mergers, and to infer source physics from EM signals.