Modelling the formation of the first two neutron star-black hole mergers, GW200105 and GW200115: metallicity, chirp masses, and merger remnant spins

Chattopadhyay, Debatri, Stevenson, Simon, Broekgaarden, Floor, Antonini, Fabio ORCID: https://orcid.org/0000-0003-3138-6199 and Belczynski, Krzysztof 2022. Modelling the formation of the first two neutron star-black hole mergers, GW200105 and GW200115: metallicity, chirp masses, and merger remnant spins. Monthly Notices of the Royal Astronomical Society 513 (4) , 5780–5789. 10.1093/mnras/stac1283

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Abstract

The two neutron star–black hole mergers (GW200105 and GW200115) observed in gravitational waves by advanced LIGO and Virgo, mark the first ever discovery of such binaries in nature. We study these two neutron star–black hole systems through isolated binary evolution, using a grid of population synthesis models. Using both mass and spin observations (chirp mass, effective spin, and remnant spin) of the binaries, we probe their different possible formation channels in different metallicity environments. Our models only support LIGO data when assuming the black hole is non-spinning. Our results show a strong preference that GW200105 and GW200115 formed from stars with sub-solar metallicities Z ≲ 0.005. Only two metal-rich (Z = 0.02) models are in agreement with GW200115. We also find that chirp mass and remnant spins jointly aid in constraining the models, while the effective spin parameter does not add any further information. We also present the observable (i.e. post-selection effects) median values of spin and mass distribution from all our models, which may be used as a reference for future mergers. Further, we show that the remnant spin parameter distribution exhibits distinguishable features in different neutron star–black hole sub-populations. We find that non-spinning, first born black holes dominate significantly the merging neutron star–black hole population, ensuring electromagnetic counterparts to such mergers a rare affair.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	Royal Astronomical Society
ISSN:	0035-8711
Date of First Compliant Deposit:	14 September 2022
Date of Acceptance:	5 May 2022
Last Modified:	17 May 2023 08:13
URI:	https://orca.cardiff.ac.uk/id/eprint/152550

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