Implications of the LISA stochastic signal from eccentric stellar mass black hole binaries in vacuum
Abstract
Astrophysical formation channels of stellar-mass binary black holes (sBBHs) can induce significant orbital eccentricities in their early inspiral. We analyze the implications on the stochastic gravitational-wave background (SGWB) from unresolved sBBHs, which can be detected with the Laser Interferometer Space Antenna (LISA). We develop an improved SGWB model for the case of an idealized Dirac-delta eccentricity distribution, and extend it to the more astrophysical case of a thermal distribution. Using a fully Bayesian framework, we find that, if all binaries have a high initial eccentricity e0 ≳ 0.9 at an orbital frequency of forb = 10−4 Hz, the resulting SGWB can be robustly distinguished from a background of quasi-circular sBBHs. For a thermal eccentricity distribution, the SGWB is consistent with a circular model when binaries form at forb = 10−5 Hz, but leads to significant systematic biases if formation occurs at forb = 10−4 Hz. We also show that, when eccentricity is properly accounted for, environmental effects such as dynamical friction can be distinguished from vacuum evolution, but only for sufficiently dense environments with gas densities ρ≳ 10−7 g cm−3. Finally, we show that a LISA detection of the sBBH SGWB would place an upper bound on the maximum eccentricity of the sBBH population in the band of ground-based detectors, with direct implications for template modeling and data analysis. Our results highlight the importance of incorporating eccentricity in SGWB modeling to enable accurate astrophysical interpretation of LISA observations.
Versions
Related
- Impact of Stochastic Pop III X-ray Binaries on the Cosmological 21-cm Signal
- Parameter Estimation for Eccentric Supermassive Black Hole Binaries with Pulsar Timing Arrays
- A parametrized test of general relativity for inspiralling eccentric binaries in LISA
- Pulsed Accretion onto Eccentric Binaries in Highly Misaligned Circumbinary Disks
- Pulsed Accretion onto Eccentric Binaries in Highly Misaligned Circumbinary Disks
BibTeX
@misc{chen2026implications,
title = {{Implications of the LISA stochastic signal from eccentric stellar mass black hole binaries in vacuum}},
author = {Ran Chen and Rohit S. Chandramouli and Federico Pozzoli and Riccardo Buscicchio and Enrico Barausse},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2605.05537},
eprint = {2605.05537},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.05537},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Implications of the LISA stochastic signal from eccentric stellar mass black hole binaries in vacuum
AU - Ran Chen
AU - Rohit S. Chandramouli
AU - Federico Pozzoli
AU - Riccardo Buscicchio
AU - Enrico Barausse
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2605.05537
UR - https://arxiv.org/abs/2605.05537
AB - Astrophysical formation channels of stellar-mass binary black holes (sBBHs) can induce significant orbital eccentricities in their early inspiral. We analyze the implications on the stochastic gravitational-wave background (SGWB) from unresolved sBBHs, which can be detected with the Laser Interferometer Space Antenna (LISA). We develop an improved SGWB model for the case of an idealized Dirac-delta eccentricity distribution, and extend it to the more astrophysical case of a thermal distribution. Using a fully Bayesian framework, we find that, if all binaries have a high initial eccentricity e_0 ≳ 0.9 at an orbital frequency of f_orb = 10^−4 Hz, the resulting SGWB can be robustly distinguished from a background of quasi-circular sBBHs. For a thermal eccentricity distribution, the SGWB is consistent with a circular model when binaries form at f_orb = 10^−5 Hz, but leads to significant systematic biases if formation occurs at f_orb = 10^−4 Hz. We also show that, when eccentricity is properly accounted for, environmental effects such as dynamical friction can be distinguished from vacuum evolution, but only for sufficiently dense environments with gas densities ρ≳ 10^−7 g cm^−3. Finally, we show that a LISA detection of the sBBH SGWB would place an upper bound on the maximum eccentricity of the sBBH population in the band of ground-based detectors, with direct implications for template modeling and data analysis. Our results highlight the importance of incorporating eccentricity in SGWB modeling to enable accurate astrophysical interpretation of LISA observations.
ER -