Gravitational wave bursts from the Galactic massive black hole

Clovis Hopman1, Marc Freitag2 and Shane L. Larson3

1Leiden University, Leiden Observatory, P.O. Box 9513, NL-2300 RA Leiden 2 Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA Cambridge, UK 3Department of Physics, Weber State University, Ogden, UT 84408

Paper: astro-ph/0612337 (submitted to MNRAS)

EPrint Server: astro-ph/0612337


Abstract:

The Galactic massive black hole (MBH), with a mass of Mbh=3.6*106 Mo, is the closest known MBH, at a distance of only 8 kpc. The proximity of this MBH makes it possible to observe gravitational waves from stars with periapse in the observational frequency window of the Laser Interferometer Space Antenna (LISA). This is possible even if the orbit of the star is very eccentric, so that the orbital frequency is many orders of magnitude below the LISA frequency window, as suggested by Rubbo et al. (2006). Here we give an analytical estimate of the detection rate of such gravitational wave bursts. The burst rate is critically sensitive to the inner cut-off of the stellar density profile. Our model accounts for mass-segregation and for the physics determining the inner radius of the cusp, such as stellar collisions, energy dissipation by gravitational wave emission, and consequences of the finite number of stars. We find that stellar black holes have a burst rate of the order of 1/yr, while the rate is of order <0.1/yr for main sequence stars and white dwarfs. These analytical estimates are supported by a series of Monte Carlo samplings of the expected distribution of stars around the Galactic MBH, which yield the full probability distribution for the rates. We estimate that no burst will be observable from the Virgo cluster.


Preprints available from the authors at clovis@strw.leidenuniv.nl , or the raw TeX (no figures) if you click here.

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