Black hole–neutron star and binary neutron star mergers from Population III and II stars
Year: 2025
Type: article
Abstract: Population III (Pop. III) stars are expected to be massive and to undergo minimal mass loss due to their lack of metals, making them ideal progenitors of black holes and neutron stars. Here, we investigate the formation and properties of binary neutron star (BNS) and black hole-neutron star (BHNS) mergers originating from Pop. III stars, and compare them to their metal-enriched Population II (Pop. II) counterparts, focusing on their merger rate densities (MRDs), primary masses, and delay times. We find that, despite the high merger efficiency of Pop. III BNSs and BHNSs, their low star formation rate results in a MRD at least one order of magnitude lower than that of Pop. II stars. The MRD of Pop. III BNSs peaks at redshift z ~ 15, attaining a value R BNS ( z ~ 15) ~ 15 Gpc −3 yr −1 , while the MRD of Pop. III BHNSs is maximum at z ~ 13, reaching a value of R BHNS ( z ~ 13) ~ 2Gpc −3 yr −1 . Finally, we observe that the black hole masses of Pop. III BHNS mergers have a nearly flat distribution, with a peak at ∼20 M ⊙ and extending up to ∼50 M ⊙ . Black holes in Pop. II BHNS mergers instead show a peak at ≲ 15 M ⊙ . We consider these predictions in light of recent gravitational-wave observations in the local Universe, finding that a Pop. III origin is preferred relative to Pop. II for some events.
Source: Astronomy and Astrophysics
Institutions: Heidelberg University, Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Gran Sasso, Gran Sasso Science Institute, University of Padua, Istituto Nazionale di Fisica Nucleare, Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Osservatorio Astronomico di Padova, National Institute for Astrophysics, Collurania Teramo Observatory, Institut de Ciències del Cosmos, Universitat de Barcelona, Massachusetts Institute of Technology, Harvard University, Center for Astrophysics Harvard & Smithsonian
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Awards: G1224374757, G1244305882, G1255325603, G1277975267, G136517941, LIGO Laboratory Operations and Maintenance 2019-2023, G1536733264, G1675634561, G1692958442, G2340603345, G2628649996, G3803561910, G3828378109, G4017813560, G4707917552, G4724125240, G4783087731, G4993383890, Gravitational waves from crowded environments: simulating intermediate-mass black hole formation and evolution with supercomputers., G598773271, G6018591478, Integrated Activities for the High Energy Astrophysics Domain, G6461157608, G6526081583, EXC 2181: STRUKTUREN: Emergenz in Natur, Mathematik und komplexen Daten, G7474525914, G7559426108, G7731791180, G7915813472, G8409680314, Research Infrastructure: LIGO Laboratory Operations and Maintenance 2024-2028 -- Exploring the Gravitational-Wave Cosmos
OpenAlex ID: W4415716550