Combining Transit and Radial Velocity: A Synthesized Population Model

We present a framework for estimating exoplanet occurrence rates by synthesizing constraints from radial velocity and transit surveys simultaneously. We employ approximate Bayesian computation and various mass–radius (M–R) relations to explore the population models describing these surveys, both separately and in a joint fit. Using this approach, we fit a planet distribution function of the form , with a break in the power law in mass at Mb, to planets orbiting FGK stars with periods days and masses . We find that the M–R relation from Otegi et al. (), which lets rocky and volatile-rich populations overlap in mass, allows us to find a model that is consistent with both types of surveys. Our joint fit gives (errors reflect 68.3% credible interval). This is nearly a factor of three higher than the break from transit-only considerations and an M–R relation without such an overlap. The corresponding planet–star mass ratio break may be consistent with microlensing studies ( ). The joint fit also requires that a fraction of planets in the overlap region belong to the rocky population. Our results strongly suggest that future M–R relations should account for a mixture of distinct types of planets in order to describe the observed planet population.