The Population of Eccentric Binary Black Holes: Implications for mHz Gravitational-wave Experiments
AffiliationUniv Arizona, Dept Astron
Univ Arizona, Steward Observ
Keywordsglobular clusters: general
stars: black holes
stars: kinematics and dynamics
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationFang, X., Thompson, T. A., & Hirata, C. M. (2019). The Population of Eccentric Binary Black Holes: Implications for mHz Gravitational-wave Experiments. The Astrophysical Journal, 875(1), 75.
RightsCopyright © 2019. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractThe observed binary black hole (BBH) mergers indicate a large Galactic progenitor population continuously evolving from large orbital separations and low gravitational-wave (GW) frequencies to the final merger phase. We investigate the equilibrium distribution of BBHs in the Galaxy. Given the observed BBH merger rate, we contrast the expected number of systems radiating in the low-frequency 0.1-10 mHz GW band under two assumptions: (1) that all merging systems originate from near-circular orbits, as may be indicative of isolated binary evolution, and (2) that all merging systems originate at very high eccentricity, as predicted by models of dynamically formed BBHs and triple and quadruple systems undergoing Lidov-Kozai eccentricity oscillations. We show that the equilibrium number of systems expected at every frequency is higher in the eccentric case (2) than in the circular case (1) by a factor of similar or equal to 2-15. This follows from the fact that eccentric systems spend more time than circular systems radiating in the low-frequency GW bands. The GW emission comes in pulses at periastron separated by the orbital period, which may be days to years. For a LISA-like sensitivity curve, we show that if eccentric systems contribute significantly to the observed merger rate, then similar or equal to 10 eccentric systems should be seen in the Galaxy.
VersionFinal published version
SponsorsSimons Foundation; NSF ; IBM Einstein Fellowship from the Institute for Advanced Study, Princeton; US Department of Energy; Packard Foundation; NASA