## [0901.0604] Gravitational waves from eccentric intermediate-mass black hole binaries

Authors: Pau Amaro-Seoane, Cole Miller, Marc Freitag

Date: 6 Jan 2009

Abstract: If binary intermediate-mass black holes (IMBHs; with masses between 100 and $10ˆ4 \Msun$) form in dense stellar clusters, their inspiral will be detectable with the planned Laser Interferometer Space Antenna (LISA) out to several Gpc. Here we present a study of the dynamical evolution of such binaries using a combination of direct $N$-body techniques (when the binaries are well separated) and three-body relativistic scattering experiments (when the binaries are tight enough that interactions with stars occur one at a time). We find that for reasonable IMBH masses there is only a mild effect on the structure of the surrounding cluster even though the binary binding energy can exceed the binding energy of the cluster. We demonstrate that, contrary to standard assumptions, the eccentricity in the LISA band can be in {\em some} cases as large as $\sim 0.2 - 0.3$ and that it induces a measurable phase difference from circular binaries in the last year before merger. We also show that, even though energy input from the binary decreases the density of the core and slows down interactions, the total time to coalescence is short enough (typically less than a hundred million years) that such mergers will be unique snapshots of clustered star formation.

#### Nov 17, 2009

0901.0604 (/preprints)
2009-11-17, 11:45