AAS 205th Meeting, 9-13 January 2005
Session 76 X-Ray Binaries, and Pulsars
Oral, Tuesday, January 11, 2005, 10:00-11:30am, Royal Palm 1-3

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[76.04] The Relativitic Evolution of Black Hole-Neutron Star Binaries

J.A. Faber (U. Illinois), T.W. Baumgarte (Bowdoin College), S.L. Shapiro, K. Taniguchi (U. Illinois)

We report results from our new relativistic evolution calculations of black hole-neutron star (BH-NS) binaries. The evolution equations of general relativity are treated in the conformally flat (CF) approximation. Assuming that the BH mass is significantly larger than that of the NS allows us to simplify the field equations for the NS, which we solve self-consistently in a fixed BH background spacetime. This approach guarantees that self-gravity is fully included. The NS fluid, assumed here to follow a gamma-law equation of state (EOS), is evolved using a Lagrangian SPH method. The field equations are solved by spectral methods in spheroidal coordinates. The code has been tested by comparing our results to previously computed quasi-equilibrium sequences, showing good agreement.

Our results are a crucial first step in evaluating the stability of mass transfer in extremely close BH-NS binaries. They will allow us to describe quantitatively the dynamical tidal disruption of the NS, and to determine the dependence on the initial binary parameters, including the mass ratio and assumed NS EOS. We will also discuss the implications for detecting gravitational waves from the merger of these systems, about which, in contrast to NS-NS binaries, little is currently known for systems with components of comparable mass.

JAF is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-0401533.

The author(s) of this abstract have provided an email address for comments about the abstract: jfaber@uiuc.edu

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© 2004. The American Astronomical Society.