The gravitational wave background from star–massive black hole fly-bys |
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| Authors: | Silvia Toonen Clovis Hopman Marc Freitag |
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| Institution: | Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, the Netherlands;Department of Astrophysics, IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, the Netherlands;Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA |
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| Abstract: | Stars on eccentric orbits around a massive black hole (MBH) emit bursts of gravitational waves (GWs) at periapse. Such events may be directly resolvable in the Galactic Centre. However, if the star does not spiral in, the emitted GWs are not resolvable for extragalactic MBHs, but constitute a source of background noise. We estimate the power spectrum of this extreme mass ratio burst background (EMBB) and compare it to the anticipated instrumental noise of the Laser Interferometer Space Antenna (LISA). To this end, we model the regions close to an MBH, accounting for mass segregation, and for processes that limit the presence of stars close to the MBH, such as GW inspiral and hydrodynamical collisions between stars. We find that the EMBB is dominated by GW bursts from stellar mass black holes, and the magnitude of the noise spectrum ( fS GW)1/2 is at least a factor of ～10 smaller than the instrumental noise. As an additional result of our analysis, we show that LISA is unlikely to detect relativistic bursts in the Galactic Centre. |
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| Keywords: | black hole physics gravitational waves stellar dynamics Galaxy: centre |
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