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

Foucart, Francois and Deaton, M. Brett and Duez, Matthew D. and Kidder, Lawrence E. and MacDonald, Ilana and Ott, Christian D. and Pfeiffer, Harald P. and Scheel, Mark A. and Szilágyi, Béla and Teukolsky, Saul A. (2013) Black-hole–neutron-star mergers at realistic mass ratios: Equation of state and spin orientation effects. Physical Review D, 87 (8). Art. No. 084006. ISSN 2470-0010. doi:10.1103/PhysRevD.87.084006.

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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 postmerger remnant are very sensitive to the parameters of the binary (mass ratio, black-hole spin, neutron star radius). In this paper, we study the impact of the radius of the neutron star and the alignment of the black-hole spin on black-hole–neutron-star mergers within the range of mass ratio currently deemed most likely for field binaries (M_BH∼7M_NS) and for black-hole spins large enough for the neutron star to disrupt (J_BH/M^(2)_(BH)=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) 0.01M_(⊙)–0.05M_(⊙) 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 postmerger optical and radio afterglows. (iii) Only a small fraction of the Advanced LIGO events in this parameter range have gravitational-wave signals which could offer constraints on the equation of state of the neutron star (at best ∼3% of the events for a single detector at design sensitivity). (iv) A misaligned black-hole spin works against disk formation, with less neutron-star material remaining outside of the black hole after merger, and a larger fraction of that material remaining in the tidal tail instead of the forming accretion disk. (v) Large kicks v_kick≳300  km/s can be given to the final black hole as a result of a precessing black-hole–neutron-star merger, when the disruption of the neutron star occurs just outside or within the innermost stable spherical orbit.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Foucart, Francois0000-0003-4617-4738
Duez, Matthew D.0000-0002-0050-1783
Kidder, Lawrence E.0000-0001-5392-7342
Ott, Christian D.0000-0003-4993-2055
Pfeiffer, Harald P.0000-0001-9288-519X
Teukolsky, Saul A.0000-0001-9765-4526
Additional Information:© 2013 American Physical Society. Received 23 December 2012; published 2 April 2013. The authors wish to thank Kipp Cannon, Michael Boyle, and Tanja Hinderer for useful discussions and suggestions over the course of this project; Nicolas Smith-Lefebvre for computing and providing LIGO noise curves tuned to high frequency; the members of the SXS Collaboration for their regular suggestions; and the participants of the "Rattle and Shine" workshop at KITP (Santa Barbara) for stimulating discussions relevant to this work. We thank Patrick Fraser for assistance with generating Figs. 1 and 2 and John Wendell for assistance with the other figures. M. D. D. acknowledges support through NASA Grant No. NNX11AC37G and NSF Grant No. PHY-1068243. H. P. P. gratefully acknowledges support from the NSERC of Canada, from the Canada Research Chairs Program, and from the Canadian Institute for Advanced Research. L. E. K. and S. A. T. gratefully acknowledge support from the Sherman Fairchild Foundation, and from NSF Grants No. PHY-0969111 and No. PHY-1005426. C.D. O., M. A. S., and B. S. are partially supported by NASA ATP Grant No. NNX11AC37G and NSF Grants No. PHY-1151197, No. PHY-1068881, and No. PHY-1005655, by the Sherman Fairchild Foundation, and the Alfred P. Sloan Foundation. F. F., L. E. K., and M. A. S. were partially supported by the National Science Foundation under Grant No. NSF PHY11-25915. Computations were performed on the GPC supercomputer at the SciNet HPC Consortium [88] funded by the Canada Foundation for Innovation, the Government of Ontario, Ontario Research Fund-Research Excellence, and the University of Toronto; on Briarée from University of Montreal, under the administration of Calcul Qubec and Compute Canada, supported by Canadian Foundation for Innovation (CFI), Natural Sciences and Engineering Research Council of Canada (NSERC), NanoQuébec, RMGA and the Fonds de recherche du Québec-Nature et technologies (FRQ-NT); and on the Zwicky cluster at Caltech, supported by the Sherman Fairchild Foundation and by NSF Grant No. PHY-0960291. This work also used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant No. OCI-1053575.
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Canada Research Chairs ProgramUNSPECIFIED
Canadian Institute for Advanced Research (CIFAR)UNSPECIFIED
Sherman Fairchild FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Issue or Number:8
Classification Code:PACS: 04.25.dg, 04.30.-w, 04.40.Dg, 47.75.+f
Record Number:CaltechAUTHORS:20130506-154544306
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38303
Deposited On:07 May 2013 22:43
Last Modified:09 Nov 2021 23:36

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