Eccentric signatures of stellar-mass binary black holes with circumbinary discs in LISA

Romero-Shaw, Isobel, Goorachurn, Samir, Siwek, Magdalena and Moore J., Christopher 2024. Eccentric signatures of stellar-mass binary black holes with circumbinary discs in LISA. Monthly Notices of the Royal Astronomical Society: Letters 534 (1) , L58-L64. 10.1093/mnrasl/slae081

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Abstract

Stellar-mass binary black holes may have circumbinary discs if formed through common-envelope evolution or within gaseous environments. Discs can drive binaries into wider and more eccentric orbits, while gravitational waves harden and circularize them. We combine cutting-edge evolution prescriptions for disc-driven binaries with well-known equations for gravitational-wave-driven evolution, and study the evolution of stellar-mass binary black holes. We find that binaries are driven by their disc to an equilibrium eccentricity, ⁠, that dominates their evolution. Once they transition to the GW-dominated regime their eccentricity decreases rapidly; we find that stellar-mass binary black holes with long-lived discs will likely be observed in LISA with detectable eccentricities at 0.01 Hz, with the precise value closely correlating with the binary’s initial mass ratio. This may lead stellar-mass binary black holes with CBDs observed in LISA to be confused with dynamically-formed binary black holes.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Physics and Astronomy
Publisher:	Oxford University Press
ISSN:	1745-3933
Date of First Compliant Deposit:	19 February 2026
Date of Acceptance:	26 August 2024
Last Modified:	19 Feb 2026 12:20
URI:	https://orca.cardiff.ac.uk/id/eprint/185056

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