Neutron star-black hole mergers with a nuclear equation of state and neutrino cooling: Dependence in the binary parameters

Academic Article

Abstract

  • We present a first exploration of the results of neutron star-black hole mergers using black hole masses in the most likely range of $7M_\odot-10M_\odot$, 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 ($\chi_{\rm BH}\gtrsim 0.7$), we show that the merger consistently produces large amounts of cool ($T\lesssim 1\,{\rm MeV}$), unbound, neutron-rich material ($M_{\rm ej}\sim 0.05M_\odot-0.20M_\odot$). A comparable amount of bound matter is initially divided between a hot disk ($T_{\rm max}\sim 15\,{\rm MeV}$) with typical neutrino luminosity $L_\nu\sim 10^{53}\,{\rm erg/s}$, and a cooler tidal tail. After a short period of rapid protonization of the disk lasting $\sim 10\,{\rm ms}$, 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 $M_{\rm BH}\sim 7M_\odot-10M_\odot$ 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 post-merger signals due to the radioactive decay of unbound material, and of large amounts of r-process nuclei.
  • Authors

  • Foucart, Francois
  • Deaton, M Brett
  • Duez, Matthew D
  • O'Connor, Evan
  • Ott, Christian D
  • Haas, Roland
  • Kidder, Lawrence E
  • Pfeiffer, Harald P
  • Scheel, Mark A
  • Szilagyi, Bela
  • Status

    Publication Date

  • July 10, 2014
  • Published In

  • Physical Review D  Journal
  • Keywords

  • astro-ph.HE
  • gr-qc
  • Digital Object Identifier (doi)

    Start Page

  • 024026
  • Volume

  • 90
  • Issue

  • 2