Interpreting and predicting the yield of transit surveys: Giant planets in the OGLE fields

Abstract

Transiting extrasolar planets are now discovered jointly by photometric surveys and by radial velocimetry. We want to determine whether the different data sets are compatible between themselves and with models of the evolution of extrasolar planets. We simulate directly a population of stars corresponding to the OGLE transit survey and assign them planetary companions based on radial velocimetry discoveries. We use a model of the evolution and structure of giant planets assuming a variable fraction of heavy elements. The output list of detectable planets of the simulations is compared to the real detections. We confirm that the radial velocimetry and photometric survey data sets are compatible within the statistical errors, assuming that planets with periods between 1 and 2 days are approximately 5 times less frequent than planets with periods between 2 and 5 days. We show that evolution models fitting present observational constraints predict a lack of small giant planets with large masses. We also identify distinct populations of planets: those with short periods (P < 10d) are only found in orbit around metal-rich stars with [Fe/H] > -0.07. We further confirm the relative absence of low-mass giant planets at small orbital distances.