GW200115: a non-spinning black hole -- neutron star merger

TL;DR

The paper discusses the gravitational wave detection GW200115, highlighting that the observed data is consistent with a non-spinning black hole--neutron star merger, aligning with astrophysical expectations.

Contribution

It demonstrates that assuming non-spinning components naturally explains the observed data, challenging previous interpretations of significant black hole spin.

Findings

Measurement favors non-spinning binary parameters

Large misaligned spins are not strongly supported by data

Non-spinning assumption aligns with astrophysical models

Abstract

GW200115 was the second merger of a black hole and a neutron star confidently detected through gravitational waves. Inference on the signal allows for a large black hole spin misaligned with the orbital angular momentum, but shows little support for aligned spin values. We show that this is a natural consequence of measuring the parameters of a black hole -- neutron star binary with non-spinning components while assuming the priors used in the LIGO-Virgo-KAGRA analysis. We suggest that, a priori, a non-spinning binary is more consistent with current astrophysical understanding.