Institute for Advanced Study Informal Astrophysics Seminar

ABSTRACT: The last few years have seen a tremendous increase of observational data regarding the properties of extrasolar planets. High precision radial velocity and transit observations have yielded large datasets which are important to improve our understanding of planet formation and evolution. But also other techniques like microlensing or direct imaging start to contribute information regarding other basic properties of the extrasolar planets. Bringing all these different dataset into one coherent picture to improve our theoretical understanding is challenging, as each technique is constraining a different aspect of the formation and evolution process. I will present planetary population synthesis as a useful method in this context as it allows many direct comparisons of theoretical results with observational data. For the synthesis, we use a planetary formation model which is based on the core accretion paradigm, but includes also disk migration and disk evolution. By varying the initial conditions of the model according to observed distributions of properties of protoplanetary disk (e.g. disk mass or lifetime) we synthesize planetary populations. Recently, we have extended this formation model into a self-consistently coupled formation and evolution model. Thanks to this it is now possible to compare a synthetic and the actual observed planetary population in all major characteristics, namely in their mass, semimajor axis, radius and luminosity distributions. As an application, I will show comparisons with transit observations concerning the synthetic and the observed radius distribution, the semimajor axis distribution of planets close to the star, and the mass-radius relationship. We find that the latter can only be reproduced if strongly reduced grain opacities are assumed during the formation process, establishing an interesting link between microphysical processes like grain growth during formation and observable quantities nowadays. I will finally make predictions for the luminosity distribution of massive planets for future direct imaging searches.