Exoplanet Detection with Gaia and METIS

Abstract

In the mid 2020s, the Gaia space astrometry mission and the Mid-infrared ELT Imager and Spectrograph (METIS) on the ELT are expected to allow an overlap between direct and indirect exoplanet detection techniques. The combination of astrometry and direct imaging will be the key to provide constraints on planet evolution models. As METIS is currently being developed, it is useful to estimate the size of the planet population that could be studied by both methods. This master's thesis aims to estimate the number of detectable planets based on a simulated planet population. The focus is on a sample of young, nearby stars, for which the planets are assumed to be self-luminous. The planet occurrence rates derived from radial velocity and microlensing detections are used to normalize the number of simulated planets. The expected astrometric signature, planet-star contrast, and angular separation are calculated and compared to the detection limitations of Gaia and METIS. While Gaia is predicted to detect thousands of exoplanets in general, a small number of planets is estimated to be detectable around the sample of young stars considered here. By assuming the maximum planet-star separation, planets in a wide minimum mass range of 0.4-10 Jupiter mass are estimated to be accessible by both Gaia and METIS down to semi-major axis 0.3 AU. Normalized to the occurrence rate, METIS is expected to access at 1.9 planets detected by Gaia within the semi-major axis range up to 3.9 AU. By assuming eccentric orbits and true masses, 2.9 planets could be studied by both Gaia and METIS. Planets are expected to be observed up to the largest distance of 129 pc in the sample and the oldest age of 133 Myr. In addition, 1.6 planets are estimated to be detectable around a smaller sample of M dwarfs.