Astrophysics, abstract
astro-ph/0602445
From: Kelly Holley-Bockelmann [view email]
Date: Mon, 20 Feb 2006 21:04:39 GMT (28kb)
Event Rate for Extreme Mass Ratio Burst Signals in the LISA Band
Authors: Louis J. Rubbo, Kelly Holley-Bockelmann, Lee Samuel Finn
Comments: 4 pages, submitted to ApJ Letters
Stellar mass compact objects in short period orbits about a $10^{4.5}$--$10^{7.5}$ solar mass massive black hole (MBH) are thought to be a significant continuous-wave source of gravitational radiation for the ESA/NASA Laser Interferometer Space Antenna (LISA) gravitational wave detector. However, these extreme mass-ratio inspiral sources began in long-period, nearly parabolic orbits that have multiple close encounters with the MBH. The gravitational radiation emitted during these close encounters may be detectable by LISA as a gravitational wave burst if the characteristic passage timescale is less than $10^5$ seconds. Scaling a static, spherical model to the size and mass of the Milky Way bulge we estimate an event rate of ~ 15 per year for such burst signals, detectable by LISA with signal-to-noise greater than five, originating in our galaxy. When extended to include Virgo cluster galaxies our estimate increases to a gravitational wave burst rate of ~ 18. We conclude that these extreme mass-ratio burst sources may be a steady and significant source of gravitational radiation in the LISA data streams.
http://arxiv.org/abs/astro-ph/0602445Astrophysics, abstract
astro-ph/0602470
From: Emanuele Berti [view email]
Date: Tue, 21 Feb 2006 19:03:13 GMT (37kb)
LISA observations of massive black hole mergers: event rates and issues in waveform modelling
Authors: Emanuele Berti
Comments: 13 pages, 2 figures. To appear in the proceedings of 10th Annual Gravitational Wave Data Analysis Workshop (GWDAW 10), Brownsville, Texas, 14-17 Dec 2005
The observability of gravitational waves from supermassive and intermediate-mass black holes by the forecoming Laser Interferometer Space Antenna (LISA), and the physics we can learn from the observations, will depend on two basic factors: the event rates for massive black hole mergers occurring in the LISA best sensitivity window, and our theoretical knowledge of the gravitational waveforms. We first provide a concise review of the literature on LISA event rates for massive black hole mergers, as predicted by different formation scenarios. Then we discuss what (in our view) are the most urgent issues to address in terms of waveform modelling. For massive black hole binary inspiral these include spin precession, eccentricity, the effect of high-order Post-Newtonian terms in the amplitude and phase, and an accurate prediction of the transition from inspiral to plunge. For black hole ringdown, numerical relativity will ultimately be required to determine the relative quasinormal mode excitation, and to reduce the dimensionality of the template space in matched filtering.
http://arxiv.org/abs/astro-ph/0602470