Equation of state effects in black hole–neutron star mergers
The merger dynamics of a black hole–neutron star (BHNS) binary is influenced by the neutron star equation of state (EoS) through the latter's effect on the neutron star's radius and on the character of the mass transfer onto the black hole. We study these effects by simulating a number of BHNS binaries in full general relativity using a mixed pseudospectral/finite difference code. We consider several models of the neutron star matter EoS, including Γ = 2 and Γ = 2.75 polytropes and the nuclear-theory-based Shen EoS. For models using the Shen EoS, we consider two limits for the evolution of the composition: source-free advection and instantaneous β-equilibrium. To focus on EoS effects, we fix the mass ratio to 3:1 and the initial aligned black hole spin to a/m = 0.5 for all models. We confirm earlier studies which found that more compact stars create a stronger gravitational wave signal but a smaller postmerger accretion disk. We also vary the EoS while holding the compaction fixed. All mergers are qualitatively similar, but we find signatures of the EoS in the waveform and in the tail and disk structures.
Additional Information© 2010 IOP Publishing Ltd. Received 18 December 2009, in final form 19 January 2010. Published 10 May 2010. We thank Evan O'Connor, Harald Pfeiffer and Manuel Tiglio for useful discussions. This work was supported in part by a grant from the Sherman Fairchild Foundation, by NSF grants PHY-0652952 and PHY-0652929 and NASA grant NNX09AF96G. CDO is partially supported through NSF award no AST-0855535. This research was supported in part by the NSF through TeraGrid  resources provided by LONI's Queen Bee and NCSA's Ranger clusters. Computations were also performed on the GPC supercomputer at the SciNet HPC Consortium. SciNet is funded by the Canada Foundation for Innovation under the auspices of Compute Canada; the Government of Ontario; Ontario Research Fund–Research Excellence and the University of Toronto. We thank Harald Pfeiffer for getting us access to SciNet by compiling SpEC and submitting our runs there.
Published - Duez2010p10129Classical_Quant_Grav.pdf
Submitted - 0912.3528.pdf