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Rates and characteristics of intermediate mass ratio inspirals detectable by advanced LIGO

Mandel, Ilya and Brown, Duncan A. and Gair, Jonathan R. and Miller, M. Coleman (2008) Rates and characteristics of intermediate mass ratio inspirals detectable by advanced LIGO. Astrophysical Journal, 681 (2). pp. 1431-1447. ISSN 0004-637X.

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Gravitational waves (GWs) from the inspiral of a neutron star (NS) or stellar-mass black hole (BH) into an intermediate-mass black hole (IMBH) with mass M ~ 50–350 M⊙ may be detectable by the planned advanced generation of ground-based GW interferometers. Such intermediate mass ratio inspirals (IMRIs) are most likely to be found in globular clusters. We analyze four possible IMRI formation mechanisms: (1) hardening of an NS-IMBH or BH-IMBH binary via three-body interactions, (2) hardening via Kozai resonance in a hierarchical triple system, (3) direct capture, and (4) inspiral of a CO from a tidally captured main-sequence star; we also discuss tidal effects when the inspiraling object is an NS. For each mechanism we predict the typical eccentricities of the resulting IMRIs. We find that IMRIs will have largely circularized by the time they enter the sensitivity band of ground-based detectors. Hardening of a binary via three-body interactions, which is likely to be the dominant mechanism for IMRI formation, yields eccentricities under 10^−4 when the GW frequency reaches 10 Hz. Even among IMRIs formed via direct captures, which can have the highest eccentricities, around 90% will circularize to eccentricities under 0.1 before the GW frequency reaches 10 Hz. We estimate the rate of IMRI coalescences in globular clusters and the sensitivity of a network of three Advanced LIGO detectors to the resulting GWs. We show that this detector network may see up to tens of IMRIs per year, although rates of one to a few per year may be more plausible. We also estimate the loss in signal-to-noise ratio that will result from using circular IMRI templates for data analysis and find that, for the eccentricities we expect, this loss is negligible.

Item Type:Article
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URLURL TypeDescription
Mandel, Ilya0000-0002-6134-8946
Brown, Duncan A.0000-0002-9180-5765
Miller, M. Coleman0000-0002-2666-728X
Additional Information:© 2008 The American Astronomical Society. Received 2007 May 2; accepted 2008 March 13. The authors are grateful to Sterl Phinney, Kip Thorne, Yuri Levin, Clovis Hopman, and Teviet Creighton for helpful discussions. I. M. thanks the Brinson Foundation, NASA grant NNG04GK98G, and NSF grants PHY-0601459 and PHY-0653321 for financial support. M. C. M. acknowledges support from the National Science Foundation under grant AST 06-07428. J. G.’s work was supported by St. Catharine’s College, Cambridge. D. B. acknowledges support from the LIGO Laboratory and the National Science Foundation under grant PHY-0601459. LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation and operates under cooperative agreement PHY-0107417. This paper has LIGO Document Number LIGO-P070014-00-Z.
Funding AgencyGrant Number
NSFAST 06-07428
St. Catharine’s College, CambridgeUNSPECIFIED
Subject Keywords:black hole physics; globular clusters : general; gravitational waves
Issue or Number:2
Record Number:CaltechAUTHORS:MANapj08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13831
Deposited By: Tony Diaz
Deposited On:02 Apr 2009 23:26
Last Modified:09 Mar 2020 13:19

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