Hot Jupiters from Disruption of Resonant Chains in Postdisk Evolution

Abstract

The formation of hot Jupiters has been a subject of interest in the field of exoplanet science. According to conventional scenarios, these gas giants are believed to form beyond the snow line and subsequently migrate inward. Although the early formation history of hot Jupiters is not well understood, they may emerge in resonant chains as a result of disk migration. Here we study the formation of hot Jupiters via the disruption of resonant chains after the gas disk disappears. We perform N-body simulations on planetary systems consisting of one gas giant and several super-Earths. The initial configuration involves all neighboring planet pairs being in a 3:2 mean motion resonance. We track the evolution of these resonant chains after the gas disk has vanished. Our results reveal that the resonant chains are prone to instability following the dispersal of the gas disk, with more than 80% of instabilities occurring within 3 million years. Only approximately 4% of resonant chains can survive the dynamical evolution. Notably, we find that resonant chains hosting hot Jupiters are more likely to be unstable compared to those hosting warm Jupiters. Our simulations indicate that 33% ± 4% hot Jupiters and 70% ± 4% warm Jupiters could possess nearby companions. Furthermore, incorporating the effects of general relativity and tidal dissipation increases the isolation of hot Jupiters, resulting in nearby companion occurrence rates of 20% ± 4% for hot Jupiters and 69% ± 6% for warm Jupiters.