| Abstract : | Discovered high multiplicity exoplanet systems are generally more tightly packed when compared to the solar system. Such compact multi-planet systems are often susceptible to dynamical instability. We investigate the impact of dynamical instability on the final orbital architectures of multi-planet systems using N-body simulations. Our models initially consist of eight planets placed randomly according to a power law distribution of mutual Hill separations. We find that more than 90% of our synthetic planetary systems go through a phase of dynamical instability, losing at least one planet. The surviving systems emerging from this chaotic evolution closely resemble the Kepler-detected multi-planet systems in terms of distributions of planetary masses, orbital periods, period ratios, and mutual Hill separations after taking into account transit geometry and Kepler detection efficiency. Our simulations reproduce various trends among observed Kepler planets, such as multiplicity-dependent eccentricity distribution, smaller eccentricities for larger planets, and intra-systems uniformity. These findings indicate that dynamical instabilities may have played a vital role in the final assembly of super-Earths and sub-Neptunes. |
