2006/09/30 by Motohiro Enoki, M. Enoki, Masahiro Nagashima +1 · 3 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Black Holes and Theoretical Physics #Eccentricity (behavior) #Galaxy #Gravitational wave #Noncommutative and Quantum Gravity Theories #Orbit (dynamics) #Orbital decay #Orbital eccentricity #Orbital elements #Pulsar #Spectral density #Supermassive black hole #astro-ph #gr-qc
paper · pdf · doi:10.1143/ptp.117.241
published as Prog.Theor.Phys. 117 (2007) 241-256 · 16 pages, 12 figures, typos correced, matched to the published version
openalex publication_date 2007/02/01 · arxiv created 2007/02/23 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
A compact binary in an eccentric orbit radiates gravitational waves (GWs) at all integer harmonics of its orbital frequency. In this study, we investigate the effect of orbital eccentricity on the expected gravitational background radiation (GWBR) from supermassive black hole (SMBH) binaries in the nuclei of galaxies. For this purpose, we formulate a power spectrum of the GWBR from cosmological evolving eccentric binaries. Then, we apply this formulation to the case of the GWBR from SMBH binaries. The key to doing this is to correctly estimate the number density of coalescing SMBH binaries. In this study, we use a semi-analytic model of galaxy and SMBH formation. We find that the power spectrum of the GWBR from SMBH binaries on eccentric orbits is suppressed for frequencies f ≲ 1 nHz if the initial eccentricity, e0, satisfies e0 > 0.2 and the initial semi-major axis is 300 times Scwarzschild radius. Our model predicts that while the overall shape and amplitude of the power spectrum depend strongly on the processes of galaxy formation, the eccentricity of binaries can affect the shape of the power spectrum for lower frequencies, i.e., f ≲ 1 nHz. Pulsar timing measurements, which can detect GW in this frequency range, could constrain the effect of eccentricity on the power spectrum of the GWBR from SMBH binaries.