The Heavy Tailed Non-Gaussianity of the Supermassive Black Hole Gravitational Wave Background

Fuente: arXiv
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Autori principali: Raidal, Juhan, Urrutia, Juan, Vaskonen, Ville, Veermäe, Hardi
Natura: Preprint
Pubblicazione: 2026
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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 study the non-Gaussian features of the gravitational wave (GW) background generated by a population of inspiraling supermassive black hole (SMBH) binaries. We show that the SMBH GW amplitude distribution (GWAD) features a universal heavy power-law tail $\propto A^{-4}$, while the low-amplitude tail depends on the SMBH merger rate and the energy-loss mechanisms of the binaries. The distribution of the induced timing residuals inherits this heavy tail. As a result, the ensemble averaged statistical moments of order three and higher diverge, limiting their usefulness as measures of non-Gaussianity, and the GW background from SMBH binaries exhibits the single loud source principle, according to which the strongest signals are more likely to be caused by a small number of loud sources. We confirm that the variance-averaged Gaussian approximation accurately describes the timing residual statistics. This approximation justifies a factored likelihood structure that combines standard Gaussian-process PTA posteriors with the non-Gaussian population prior, enabling consistent incorporation of non-Gaussian effects into SMBH model inference. We provide a fast and flexible Python implementation to compute the distribution of timing residuals from a given SMBH merger rate or GWAD.
format Preprint
id arxiv_https___arxiv_org_abs_2604_08506
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Heavy Tailed Non-Gaussianity of the Supermassive Black Hole Gravitational Wave Background
Raidal, Juhan
Urrutia, Juan
Vaskonen, Ville
Veermäe, Hardi
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
We study the non-Gaussian features of the gravitational wave (GW) background generated by a population of inspiraling supermassive black hole (SMBH) binaries. We show that the SMBH GW amplitude distribution (GWAD) features a universal heavy power-law tail $\propto A^{-4}$, while the low-amplitude tail depends on the SMBH merger rate and the energy-loss mechanisms of the binaries. The distribution of the induced timing residuals inherits this heavy tail. As a result, the ensemble averaged statistical moments of order three and higher diverge, limiting their usefulness as measures of non-Gaussianity, and the GW background from SMBH binaries exhibits the single loud source principle, according to which the strongest signals are more likely to be caused by a small number of loud sources. We confirm that the variance-averaged Gaussian approximation accurately describes the timing residual statistics. This approximation justifies a factored likelihood structure that combines standard Gaussian-process PTA posteriors with the non-Gaussian population prior, enabling consistent incorporation of non-Gaussian effects into SMBH model inference. We provide a fast and flexible Python implementation to compute the distribution of timing residuals from a given SMBH merger rate or GWAD.
title The Heavy Tailed Non-Gaussianity of the Supermassive Black Hole Gravitational Wave Background
topic Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2604.08506