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 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$).