Mergers of black hole-neutron star binaries. I. Methods and first results

Emmanouela Rantsiou*, Shiho Kobayashi, Pablo Laguna, Frederic A. Rasio

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


We use a 3D relativistic SPH (smoothed particle hydrodynamics) code to study mergers of black hole-neutron star (BH-NS) binary systems with low mass ratios, adopting ≡ MNS/MBH ≃ 0.1 as a representative case. The outcome of such mergers depends sensitively on both the magnitude of the BH spin and its obliquity (i.e., the inclination of the binary orbit with respect to the equatorial plane of the BH). In particular, only systems with sufficiently high BH spin parameter a and sufficiently low orbital inclinations allow any NS matter to escape or to form a long-lived disk outside the BH horizon after disruption. Mergers of binaries with orbital inclinations above ∼60° lead to complete prompt accretion of the entire NS by the BH, even for the case of an extreme Kerr BH. We find that the formation of a significant disk or torus of NS material around the BH always requires a near-maximal BH spin and a low initial inclination of the NS orbit just prior to merger.

Original languageEnglish (US)
Pages (from-to)1326-1349
Number of pages24
JournalAstrophysical Journal
Issue number2
StatePublished - Jun 20 2008


  • Binaries: close
  • Black hole physics
  • Gamma rays: bursts
  • Relativity
  • Stars: neutron

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Mergers of black hole-neutron star binaries. I. Methods and first results'. Together they form a unique fingerprint.

Cite this