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Numerical simulations of neutron star-black hole binaries in the near-equal-mass regime

Foucart, F. and Duez, M. D. and Kidder, L. E. and Nissanke, S. M. and Pfeiffer, H. P. and Scheel, M. A. (2019) Numerical simulations of neutron star-black hole binaries in the near-equal-mass regime. Physical Review D, 99 (10). Art. No. 103025. ISSN 2470-0010. https://resolver.caltech.edu/CaltechAUTHORS:20190530-092044146

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Abstract

Simulations of neutron star–black hole (NSBH) binaries generally consider black holes with masses in the range (5–10)M⊙, where we expect to find most stellar mass black holes. The existence of lower mass black holes, however, cannot be theoretically ruled out. Low-mass black holes in binary systems with a neutron star companion could mimic neutron star–neutron star (NSNS) binaries, as they power similar gravitational waves and electromagnetic signals. To understand the differences and similarities between NSNS mergers and low-mass NSBH mergers, numerical simulations are required. Here, we perform a set of simulations of low-mass NSBH mergers, including systems compatible with GW170817. Our simulations use a composition and temperature dependent equation of state (DD2) and approximate neutrino transport, but no magnetic fields. We find that low-mass NSBH mergers produce remnant disks significantly less massive than previously expected, and consistent with the postmerger outflow mass inferred from GW170817 for a moderately asymmetric mass ratio. Whether postmerger disk outflows can also explain the inferred velocity and composition of that event’s ejecta is an open question that our merger simulations cannot answer at this point. The dynamical ejecta produced by systems compatible with GW170817 are negligible except if the mass ratio and black hole spin are at the edge of the allowed parameter space. The dynamical ejecta are cold, neutron-rich, and surprisingly slow for ejecta produced during the tidal disruption of a neutron star: v∼(0.1–0.15)c. We also find that the final mass of the remnant black hole is consistent with existing analytical predictions, while the final spin of that black hole is noticeably larger than expected—up to χ_(BH) = 0.84 for our equal mass case.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1103/physrevd.99.103025DOIArticle
https://arxiv.org/abs/1903.09166arXivDiscussion Paper
ORCID:
AuthorORCID
Foucart, F.0000-0003-4617-4738
Duez, M. D.0000-0002-0050-1783
Kidder, L. E.0000-0001-5392-7342
Nissanke, S. M.0000-0001-6573-7773
Pfeiffer, H. P.0000-0001-9288-519X
Additional Information:© 2019 American Physical Society. Received 25 March 2019; published 30 May 2019. The authors thank Tanja Hinderer as well as the members of the SXS Collaboration for helpful discussions over the course of this project. F. F. gratefully acknowledges support from NASA through Grant No. 80NSSC18K0565 and from the NSF through Grant No. PHY-1806278. M. D. acknowledges support through NSF Grant No. PHY-1806207. S. M. N. is grateful for support from NWO VIDI and TOP Grants of the Innovational Research Incentives Scheme (Vernieuwingsimpuls) financed by the Netherlands Organization for Scientific Research (NWO). H. P. gratefully acknowledges support from the NSERC Canada. L. K. acknowledges support from NSF Grant No. PHY-1606654. M. S. acknowledges support from NSF Grants No. PHY-170212 and No. PHY-1708213. L. K. and M. S. also thank the Sherman Fairchild Foundation for their support. Computations were performed on the supercomputer Briarée from the Université de Montréal, managed by Calcul Québec and Compute Canada. The operation of these supercomputers is funded by the Canada Foundation for Innovation (CFI), NanoQuébec, Réseau de Médecine Génétique Appliquée (RMGA), and the Fonds de recherche du Québec—Nature et Technologie (FRQ-NT). Computations were also performed on the Zwicky and Wheeler clusters at Caltech, supported by the Sherman Fairchild Foundation and by NSF Award No. PHY-0960291.
Group:TAPIR, Walter Burke Institute for Theoretical Physics
Funders:
Funding AgencyGrant Number
NASA80NSSC18K0565
NSFPHY-1806278
NSFPHY-1806207
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
NSFPHY-1606654
NSFPHY-170212
NSFPHY-1708213
Sherman Fairchild FoundationUNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
NanoQuébecUNSPECIFIED
Réseau de Médecine Génétique Appliquée (RMGA)UNSPECIFIED
Fonds de recherche du Québec - Nature et technologies (FRQNT)UNSPECIFIED
NSFPHY-0960291
Issue or Number:10
Record Number:CaltechAUTHORS:20190530-092044146
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190530-092044146
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95953
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:30 May 2019 16:28
Last Modified:09 Mar 2020 13:19

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