Abstract

The gravitational instability (GI) theory of planet/brown dwarf formation proposes that self-gravitating discs could fragment to form bound objects. These objects are predicted to possess initial masses of around 3 Jupiter masses or larger. We now have the tools to probe GI in action, thanks to ALMA ’s recent advances in detecting both spiral structure (Perez et al 2016) and the fragmentation process (Tobin et al 2016).

The raises the possibility that the exoplanet population, while largely assembled by core accretion, could contain a “contaminant” subset of massive planets formed via GI. More recent “tidal downsizing” theories suggest that this contamination could extend well into the Neptune regime and beyond. We must now ask – what does the population of objects predicted by the latest GI theory look like?

The only way we can achieve the statistical power needed to answer these questions is with population synthesis models, which until recently only existed for core accretion. I will describe our ground-breaking population synthesis models of GI, and discuss their implications for interpreting current and future exoplanet data.