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Free keywords:
Astrophysics, Earth and Planetary Astrophysics, astro-ph.EP, Astrophysics, Instrumentation and Methods for Astrophysics, astro-ph.IM, Astrophysics, Solar and Stellar Astrophysics, astro-ph.SR,General Relativity and Quantum Cosmology, gr-qc
Abstract:
The Laser Interferometer Space Antenna (LISA) will detect and characterize
$\sim10^4$ Galactic Binaries consisting predominantly of two White Dwarfs (WD).
An interesting prospect within this population is a third object--another WD
star, a Circumbinary Exoplanet (CBP), or a Brown Dwarf (BD)--in orbit about the
inner WD pair. We present the first fully Bayesian detection and posterior
analysis of sub-stellar objects with LISA, focusing on the characterization of
CBPs. We used an optimistic astrophysically motivated catalogue of these CBP
third-body sources, including their orbital eccentricity around the inner
binary for the first time. We examined Bayesian Evidence computations for
detectability, as well as the effects on the posterior distributions for both
the inner binary parameters and the third-body parameters. We find that the
posterior behavior bifurcates based on whether the third-body period is above
or below half the observation time. Additionally, we find that undetectable
third-body sources can bias the inner binary parameters whether or not the
correct template is used. We used the information retrieved from the study of
the CBP population to make an initial conservative prediction for the number of
detectable BD systems in the original catalogue. We end with commentary on the
predicted qualitative effects on LISA global fitting and Galactic Binary
population analysis. The procedure used in this work is generic and can be
directly applied to other astrophysical effects expected within the Galactic
Binary population.
