Eccentricity effects on the supermassive black hole gravitational wave background

Fuente: arXiv
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Main Authors: Raidal, Juhan, Urrutia, Juan, Vaskonen, Ville, Veermäe, Hardi
Format: Preprint
Published: 2024
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author Raidal, Juhan
Urrutia, Juan
Vaskonen, Ville
Veermäe, Hardi
author_facet Raidal, Juhan
Urrutia, Juan
Vaskonen, Ville
Veermäe, Hardi
contents We studied how eccentricity affects the gravitational wave (GW) spectrum from supermassive black hole (SMBH) binaries. We developed a fast and accurate semi-analytic method for computing the GW spectra, the distribution for the spectral fluctuations and the correlations between different frequencies. As GW emission circularizes binaries, the suppression of the signal strength due to eccentricity is relevant for signals from wider binaries emitting at lower frequencies. Such a feature is present in the signal observed at pulsar timing arrays. We found that when orbital decay of the SMBH binaries is driven by GWs only, the shape of the observed signal preferred highly eccentric binaries $\langle e \rangle_{2\,{\rm nHz}} = 0.83^{+0.04}_{-0.05}$. However, when environmental effects were included, the initial eccentricity could be significantly lowered, yet the scenario with purely circular binaries was still mildly disfavored.
format Preprint
id arxiv_https___arxiv_org_abs_2406_05125
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Eccentricity effects on the supermassive black hole gravitational wave background
Raidal, Juhan
Urrutia, Juan
Vaskonen, Ville
Veermäe, Hardi
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
We studied how eccentricity affects the gravitational wave (GW) spectrum from supermassive black hole (SMBH) binaries. We developed a fast and accurate semi-analytic method for computing the GW spectra, the distribution for the spectral fluctuations and the correlations between different frequencies. As GW emission circularizes binaries, the suppression of the signal strength due to eccentricity is relevant for signals from wider binaries emitting at lower frequencies. Such a feature is present in the signal observed at pulsar timing arrays. We found that when orbital decay of the SMBH binaries is driven by GWs only, the shape of the observed signal preferred highly eccentric binaries $\langle e \rangle_{2\,{\rm nHz}} = 0.83^{+0.04}_{-0.05}$. However, when environmental effects were included, the initial eccentricity could be significantly lowered, yet the scenario with purely circular binaries was still mildly disfavored.
title Eccentricity effects on the supermassive black hole gravitational wave background
topic Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2406.05125