Neutron star-black hole mergers with a nuclear equation of state and neutrino cooling: Dependence in the binary parameters
We present a first exploration of the results of neutron star-black hole mergers using black hole masses in the most likely range of 7M_⊙ –10M_⊙, a neutrino leakage scheme, and a modeling of the neutron star material through a finite-temperature nuclear-theory based equation of state. In the range of black hole spins in which the neutron star is tidally disrupted (χ BH ≳0.7), we show that the merger consistently produces large amounts of cool (T≲1 MeV), unbound, neutron-rich material (M_(ej) ∼ 0.05M_⊙ –0.20M_⊙). A comparable amount of bound matter is initially divided between a hot disk (T_(max) ∼15 MeV) with typical neutrino luminosity of L_ ν ∼10^(53) erg/s, and a cooler tidal tail. After a short period of rapid protonization of the disk lasting ∼10 ms, the accretion disk cools down under the combined effects of the fall-back of cool material from the tail, continued accretion of the hottest material onto the black hole, and neutrino emission. As the temperature decreases, the disk progressively becomes more neutron rich, with dimmer neutrino emission. This cooling process should stop once the viscous heating in the disk (not included in our simulations) balances the cooling. These mergers of neutron star-black hole binaries with black hole masses of M_(BH) ∼7M_⊙ –10M_⊙, and black hole spins high enough for the neutron star to disrupt provide promising candidates for the production of short gamma-ray bursts, of bright infrared postmerger signals due to the radioactive decay of unbound material, and of large amounts of r-process nuclei.
Additional Information© 2014 American Physical Society. Received 7 May 2014; Published 10 July 2014. The authors thank Luke Roberts, Curran Muhlberger, Nick Stone, Carlos Palenzuela, Albino Perego, Zach Etienne, and Alexander Tchekhovskoy for useful discussions over the course of this project, and the members of the SXS collaboration and the participants and organizers of the MICRA 2013 workshop for their suggestions and support. F. F. gratefully acknowledges support from the Vincent and Beatrice Tremaine Postdoctoral Fellowship. The authors at CITA gratefully acknowledge support from the NSERC Canada, from the Canada Research Chairs Program, and from the Canadian Institute for Advanced Research. M. D. D. and M. B. D. acknowledge support through NASA Grant No. NNX11AC37G and NSF Grant No. PHY-1068243. L. K. gratefully acknowledges support from NSF Grants No. PHY-1306125 and No. AST-1333129, while the authors at Caltech acknowledge support from NSF Grants No. PHY-1068881 and No. AST-1333520 and NSF CAREER Grant No. PHY-1151197. Authors at both Caltech and Cornell 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 this supercomputer is funded by the Canada Foundation for Innovation (CFI), NanoQuébec, RMGA, and the Fonds de recherche du Québec—Nature et Technologie (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) through Grant No. TG-PHY990007N, supported by NSF Grant No. ACI-1053575.
Published - PhysRevD.90.024026.pdf
Submitted - 1405.1121v2.pdf