LISA verification binaries with updated distances from Gaia Data Release 2

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 to 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 Gaia Data Release 2 we calculate signal-to-noise ratios (SNR) for ≈50 verification binary candidates. We find that 11 binaries reach an SNR ≥ 20, two further binaries reaching an SNR≥ 5, and three more systems are expected to have a SNR≈ 5 after 4 yr integration with LISA. For these 16 systems, we present predictions of the gravitational wave amplitude (A) and parameter uncertainties from Fisher information matrix on the amplitude (A) and inclination (ι).