The Role of Corecollapse Physics in the Observability of Black Hole Neutron Star Mergers as Multimessenger Sources
Abstract
Recent 1D corecollapse simulations indicate a nonmonotonicity of the explodability of massive stars with respect to their precollapse core masses, which is in contrast to commonly used prescriptions. In this work, we explore the implications of these results on the formation of coalescing black hole (BH)neutron star (NS) binaries. Furthermore, we investigate the effects of natal kicks and the NS's radius on the synthesis of such systems and potential electromagnetic counterparts (EMCs) linked to them. Models based on 1D corecollapse simulations result in a BHNS merger detection rate ( ∼ 2.3 yr^{1}), 510 times larger than the predictions of "standard" prescriptions. This is primarily due to the formation of lowmass BHs via direct collapse, and hence no natal kicks, favored by the 1D simulations. The fraction of observed systems that will produce an EMC, with the supernova engine from 1D simulations, ranges from 2% to 25%, depending on the NS equation of state. Notably, in most merging systems with EMCs, the NS is the firstborn compact object, as long as the NS's radius is ≲ 12 km. Furthermore, models with negligible kicks for lowmass BHs increase the detection rate of GW190426_152155like events to ∼ 0.6 yr^{1}, with an associated probability of EMC ≤10% for all supernova engines. Finally, models based on 1D corecollapse simulations predict a ratio of BHNSs to binary BHs' merger rate density that is at least twice as high as other prescriptions, but at the same time overpredicting the measured local merger density rate of binary black holes.
 Publication:

The Astrophysical Journal
 Pub Date:
 May 2021
 DOI:
 10.3847/20418213/abf42c
 arXiv:
 arXiv:2012.02274
 Bibcode:
 2021ApJ...912L..23R
 Keywords:

 Gravitational waves;
 Black holes;
 Neutron stars;
 Binary stars;
 678;
 162;
 1108;
 154;
 Astrophysics  High Energy Astrophysical Phenomena;
 Astrophysics  Solar and Stellar Astrophysics;
 General Relativity and Quantum Cosmology
 EPrint:
 13 pages, 5 figures, 3 tables