The Scientific Discovery Space for the Roman Galactic Bulge Time Domain Survey

Maximizing the scientific return of Roman requires focusing on the scientific discovery space opened up by Roman relative to the ground: i.e., planets in wide orbits (log s > 0.4), the smallest mass-ratio planets (log q < -4.5), and free-floating planet candidates (especially those with thetaE < 1 uas). However, capitalizing on that leverage requires not just detecting such planets but characterizing them sufficiently that they can be used in a statistical analysis. In particular, the signals from all three categories are all prone to light curve degeneracies that may lead to ambiguities in the planet mass-ratio q, separation s, and the size of the source rho (used to measure thetaE and constrain the host mass). Bound planets may also have light curves that are degenerate with models that include a second source rather than a planet. The most immediate need for designing the Roman Galactic Bulge Time Domain Survey is a detailed simulation of wide-orbit and small planetary perturbations to investigate how well the planet perturbations will be characterized. These investigations and related trade-studies must be done in order to maximize Roman's ability to take advantage of new parameter space.