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Main Authors: Chen, Ran, Chandramouli, Rohit S., Pozzoli, Federico, Buscicchio, Riccardo, Barausse, Enrico
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.00694
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author Chen, Ran
Chandramouli, Rohit S.
Pozzoli, Federico
Buscicchio, Riccardo
Barausse, Enrico
author_facet Chen, Ran
Chandramouli, Rohit S.
Pozzoli, Federico
Buscicchio, Riccardo
Barausse, Enrico
contents The population of unresolved stellar-mass black hole binaries (sBBHs) is expected to produce a stochastic gravitational-wave background (SGWB) potentially detectable by the Laser Interferometer Space Antenna (LISA). In this work, we compute the imprint of astrophysical environmental effect--such as gas dynamical friction and accretion--on this background. Using the sBBHs population constraints obtained by the LIGO--Virgo--Kagra collaboration, we compute the expected SGWB and develop a phenomenological parametric model that can accurately capture the effect of dynamical friction and accretion. Using our model, we perform Bayesian inference on simulated signals to assess the detectability of these environmental effects. We find that even for large injected values of the Eddington ratio, the effect of accretion in the SGWB is undetectable by LISA. However, LISA will be able to constrain the effect of dynamical friction with an upper bound on the gas density of $ρ\lesssim 7.6 \times 10^{-10} \mathrm{g \, cm^{-3}}$, thus probing the sBBH environment forming in typical thin accretion disks around Active Galactic Nuclei (AGNs). For injected densities of $ρ\sim 10^{-10}-10^{-9} \mathrm{g} \, \mathrm{cm}^{-3}$, dynamical friction effects can be well measured and clearly distinguished from vacuum, with Bayes factors reaching up to $\sim$ 60, even when the Galactic foreground is included.
format Preprint
id arxiv_https___arxiv_org_abs_2507_00694
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Muffled Murmurs: Environmental effects in the LISA stochastic signal from stellar-mass black hole binaries
Chen, Ran
Chandramouli, Rohit S.
Pozzoli, Federico
Buscicchio, Riccardo
Barausse, Enrico
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
The population of unresolved stellar-mass black hole binaries (sBBHs) is expected to produce a stochastic gravitational-wave background (SGWB) potentially detectable by the Laser Interferometer Space Antenna (LISA). In this work, we compute the imprint of astrophysical environmental effect--such as gas dynamical friction and accretion--on this background. Using the sBBHs population constraints obtained by the LIGO--Virgo--Kagra collaboration, we compute the expected SGWB and develop a phenomenological parametric model that can accurately capture the effect of dynamical friction and accretion. Using our model, we perform Bayesian inference on simulated signals to assess the detectability of these environmental effects. We find that even for large injected values of the Eddington ratio, the effect of accretion in the SGWB is undetectable by LISA. However, LISA will be able to constrain the effect of dynamical friction with an upper bound on the gas density of $ρ\lesssim 7.6 \times 10^{-10} \mathrm{g \, cm^{-3}}$, thus probing the sBBH environment forming in typical thin accretion disks around Active Galactic Nuclei (AGNs). For injected densities of $ρ\sim 10^{-10}-10^{-9} \mathrm{g} \, \mathrm{cm}^{-3}$, dynamical friction effects can be well measured and clearly distinguished from vacuum, with Bayes factors reaching up to $\sim$ 60, even when the Galactic foreground is included.
title Muffled Murmurs: Environmental effects in the LISA stochastic signal from stellar-mass black hole binaries
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2507.00694