LISA verification binaries with updated distances from Gaia Data Release 2

TL;DR

This paper updates the expected gravitational wave signals from verification binaries for LISA using Gaia DR2 distances, identifying 16 systems with significant detection prospects and providing detailed parameter predictions.

Contribution

It provides revised SNR estimates and parameter uncertainties for verification binaries based on Gaia DR2 parallaxes, improving gravitational wave source predictions for LISA.

Findings

11 binaries with SNR ≥ 20 predicted

2 binaries with SNR ≥ 5 predicted

3 additional systems expected to have SNR ≈ 5 after four years

Abstract

Ultracompact binaries with orbital periods less than a few hours will dominate the gravitational wave signal in the mHz regime. Until recently, 10 systems were expected have a predicted gravitational wave signal strong enough to be detectable by the Laser Interferometer Space Antenna (LISA), the so-called `verification binaries'. System parameters, including distances, are needed to provide an accurate prediction of the expected gravitational wave strength to be measured by LISA. Using parallaxes from {\sl Gaia} Data Release 2 we calculate signal-to-noise ratios (SNR) for $\approx$50 verification binary candidates. We find that 11 binaries reach a SNR$\geq$20, two further binaries reaching a SNR$\geq$5 and three more systems are expected to have a SNR$\approx$5 after four years integration with LISA. For these 16 systems we present predictions of the gravitational wave amplitude ($\mathcal{A}$) and parameter uncertainties from Fisher information matrix on the amplitude ($\mathcal{A}$) and inclination ($\iota$).