Black hole-neutron star mergers at realistic mass ratios: Equation of state and spin orientation effects

Black hole-neutron star mergers resulting in the disruption of the neutron star and the formation of an accretion disk and/or the ejection of unbound material are prime candidates for the joint detection of gravitational-wave and electromagnetic signals when the next generation of gravitational-wave...

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Bibliographic Details
Published in:arXiv.org 2013-04
Main Authors: Foucart, Francois, Deaton, M Brett, Duez, Matthew D, Kidder, Lawrence E, MacDonald, Ilana, Ott, Christian D, Pfeiffer, Harald P, Scheel, Mark A, Szilagyi, Bela, Teukolsky, Saul A
Format: Article
Language:English
Subjects:
Accretion disks
Afterglows
Disruption
Ejecta
Equations of state
Gravitation
Gravitational waves
Kinetic energy
Mass ratios
Neutron stars
Neutrons
Orbital stability
Parameter sensitivity
Signal generation
Star mergers
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Summary:Black hole-neutron star mergers resulting in the disruption of the neutron star and the formation of an accretion disk and/or the ejection of unbound material are prime candidates for the joint detection of gravitational-wave and electromagnetic signals when the next generation of gravitational-wave detectors comes online. However, the disruption of the neutron star and the properties of the post-merger remnant are very sensitive to the parameters of the binary. In this paper, we study the impact of the radius of the neutron star and the alignment of the black hole spin for systems within the range of mass ratio currently deemed most likely for field binaries (M_BH ~ 7 M_NS) and for black hole spins large enough for the neutron star to disrupt (J/M^2=0.9). We find that: (i) In this regime, the merger is particularly sensitive to the radius of the neutron star, with remnant masses varying from 0.3M_NS to 0.1M_NS for changes of only 2 km in the NS radius; (ii) 0.01-0.05M_sun of unbound material can be ejected with kinetic energy >10^51 ergs, a significant increase compared to low mass ratio, low spin binaries. This ejecta could power detectable optical and radio afterglows. (iii) Only a small fraction (300 km/s) can be given to the final black hole as a result of a precessing BHNS merger, when the disruption of the neutron star occurs just outside or within the innermost stable spherical orbit.
ISSN:2331-8422
DOI:10.48550/arxiv.1212.4810