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On strong mass segregation around a massive black hole: Implications for lower-frequency gravitational-wave astrophysics

Preto, M., & Amaro-Seoane, P. (2010). On strong mass segregation around a massive black hole: Implications for lower-frequency gravitational-wave astrophysics. Astrophysical Journal, Letters, 708, L42-L46. Retrieved from http://arxiv.org/abs/0910.3206.

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Genre: Journal Article

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0910.3206 (Preprint), 269KB
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Creators:
Preto, Miguel, Author
Amaro-Seoane, Pau1, Author
Affiliations:
1Astrophysical Relativity, AEI-Golm, MPI for Gravitational Physics, Max Planck Society, ou_24013

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Free keywords: Astrophysics, Galaxy Astrophysics, astro-ph.GA,Astrophysics, Cosmology and Extragalactic Astrophysics, astro-ph.CO,General Relativity and Quantum Cosmology, gr-qc
Abstract: We present, for the first time, a clear $N$-body realization of the {\it strong mass segregation} solution for the stellar distribution around a massive black hole. We compare our $N$-body results with those obtained by solving the orbit-averaged Fokker-Planck (FP) equation in energy space. The $N$-body segregation is slightly stronger than in the FP solution, but both confirm the {\it robustness} of the regime of strong segregation when the number fraction of heavy stars is a (realistically) small fraction of the total population. In view of recent observations revealing a dearth of giant stars in the sub-parsec region of the Milky Way, we show that the time scales associated with cusp re-growth are not longer than $(0.1-0.25) \times T_{rlx}(r_h)$. These time scales are shorter than a Hubble time for black holes masses $\mbul \lesssim 4 \times 10^6 M_\odot$ and we conclude that quasi-steady, mass segregated, stellar cusps may be common around MBHs in this mass range. Since EMRI rates scale as $\mbul^{-\alpha}$, with $\alpha \in [1\4,1]$, a good fraction of these events should originate from strongly segregated stellar cusps.

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Dates: 2009-10-162009-10-182010
Publication Status: Published in print
Pages: 5 pages, 4 figures, 1 table, submitted to ApJL
Publishing info: -
Rev. Method: -
Identifiers: arXiv: 0910.3206
URI: http://arxiv.org/abs/0910.3206
Degree: -

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Title: Astrophysical Journal, Letters
Alternative Title : ApJL
Source Genre: Journal
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Publ. Info: Chicago, IL : University of Chicago Press for the American Astronomical Society
Pages: - Volume / Issue: 708 Sequence Number: - Start / End Page: L42 - L46 Identifier: DOI: 10.1088/2041-8205/708/1/L42
ISSN: 0004-637X