2021/03/03 by Floor S. Broekgaarden, Edo Berger, E. Berger +11 · 1 voice
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Binary number #Black hole (networking) #Common envelope #Gamma-ray burst #Gamma-ray bursts and supernovae #Gravitational wave #LIGO #Metallicity #Neutron star #Order (exchange) #Physics #Pulsars and Gravitational Waves Research #Stars #Supernova #White dwarf #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stab2716
38 pages, 18 figures, accepted to MNRAS. The authors welcome suggestions and feedback. All data and code to reproduce the results in this paper are publicly available
arxiv published 2021/03/03 · openalex created_date 2021/03/15 · openalex publication_date 2021/09/21 · arxiv created 2021/10/08 · arxiv updated 2021/10/11 · openalex updated_date 2026/08/06
ABSTRACT Mergers of black hole–neutron star (BHNS) binaries have now been observed by gravitational wave (GW) detectors with the recent announcement of GW200105 and GW200115. Such observations not only provide confirmation that these systems exist but will also give unique insights into the death of massive stars, the evolution of binary systems and their possible association with gamma-ray bursts, r-process enrichment, and kilonovae. Here, we perform binary population synthesis of isolated BHNS systems in order to present their merger rate and characteristics for ground-based GW observatories. We present the results for 420 different model permutations that explore key uncertainties in our assumptions about massive binary star evolution (e.g. mass transfer, common-envelope evolution, supernovae), and the metallicity-specific star formation rate density, and characterize their relative impacts on our predictions. We find intrinsic local BHNS merger rates spanning \mathcal R_\rm m0 ≈ 4–830 \rm Gpc-3 \rm yr-1 for our full range of assumptions. This encompasses the rate inferred from recent BHNS GW detections and would yield detection rates of \mathcal R_\rm det ≈ 1–180 \rm yr-1 for a GW network consisting of LIGO, Virgo, and KAGRA at design sensitivity. We find that the binary evolution and metallicity-specific star formation rate density each impacts the predicted merger rates by order \mathcal O(10). We also present predictions for the GW-detected BHNS merger properties and find that all 420 model variations predict that \lesssim 5 \rm per cent of the BHNS mergers have BH masses m_\rm BH \gtrsim 18 \rm M\odot , total masses m_\rm tot \gtrsim 20 \rm M\odot , chirp masses \mathcal M_\rm c \gtrsim 5.5 \rm M\odot , and mass ratios qf ≳ 12 or qf ≲ 2. Moreover, we find that massive NSs with m_\rm NS \gt 2 \rm M\odot are expected to be commonly detected in BHNS mergers in almost all our model variations. Finally, a wide range of ∼ 0 \rm per cent to 70 \rm per cent of the BHNS mergers are predicted to eject mass during the merger. Our results highlight the importance of considering variations in binary evolution and cosmological models when predicting, and eventually evaluating, populations of BHNS mergers.