Thousands of exoplanets have been discovered over the past three decades, mostly using methods that are only sensitive to planets orbiting a star. Gravitational microlensing has opened a window on the detection of free-floating, or rogue planets, which are apparently orphaned. Recent statistical analysis of microlensing survey observations suggests that free-floating planets vastly outnumber planets bound to stars. Does this make sense from a theoretical perspective?
The paradigm of planet formation mandates that planets form in protoplanetary disks around stars. Therefore, the most plausible source of free-floating planets is ejection from originally bound planet systems.
This master's thesis project will study the predicted rate of planet ejections from dynamical instabilities in young exoplanet systems, using N-body simulations. We will compare the characteristics of the synthetic population of ejected planets with the latest microlensing measurements, taking into consideration complicated detection biases. This comparison will help constrain the mechanisms of free-floating planet formation.
The work has implications for expected findings from NASA’s upcoming mission with the Nancy Grace Roman Space Telescope.
The candidate will learn the basic principles of gravitational microlensing as a promising method of exoplanet detection, and to run state-of-the-art numerical simulations of celestial dynamics on supercomputers.
They will also learn about our current understanding of exoplanet demographics and the importance of correcting detection biases. Interest in exoplanet science and scientific computing are assets.