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K. Holley-Bockelmann, S. Sigurdsson, L. S. Finn (Penn State University)
Once a supermassive binary black hole (SMBBH) is bound in the galactic center, 3-body scattering with stars in the binary's loss cone will shrink the orbit until the black holes are so close that further coalescence is driven by gravitational wave radiation. Idealized studies of SMBBH coalescence in spherically symmetric galaxies have long shown, however, that the loss cone is so quickly depleted that the timescale for SMBBH coalescence is much longer than a Hubble time. Centrophilic orbits found in the backbone of triaxial galaxies have been suggested as one mechanism to keep the loss cone around a SMBBH filled with stars, stellar remnants, and intermediate mass black holes; this would allow 3-body scattering to tighten the binary further and more quickly, and could lead to coalescence in less than a Hubble time.
For the first time, we directly determine the evolution of the loss cone population in triaxial galaxies with fully self-consistent high resolution N-body simulations. This is the first step in a multiphase project that will explore the dynamics of SMBBHs in realistic, fully self-consistent systems. The phase space content and time evolution of the loss cone affects SMBBH merger rates, extreme mass ratio capture rates, as well as the growth rate of a single supermassive black hole due to stellar accretion. Since these are key observables for the Laser Interferometer Space Antenna (LISA), it is clear that investigating the loss cone dynamics of supermassive black holes, when used in concert with future LISA observations, will allow us to better understand the role these black holes play in galactic structure and evolution.
The author(s) of this abstract have provided an email address for comments about the abstract: kellyhb@gravity.psu.edu
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.