Effects of Pebble Accretion Isolation Mass on Observable Exoplanet Properties

Abstract

The Kepler Mission has discovered a plethora of planetary systems with super-Earth sized planets. These systems exhibit many properties, from widely-spaced planets with non-negligible eccentricities and inclinations, to tightly-spaced, coplanar, and nearly circular multi-planet systems. The observable properties of these systems, such as planet-planet spacings, multiplicity and orbital morphology, can be strongly influenced by the initial conditions of formation. These conditions affect the early growth of planetary embryos in the gas disk phase through pebble and/or planetesimal accretion, which then affects the final growth of planets during the giant impact stage. In this work, we investigate how assumptions of different limiting embryo isolation masses during early stages of planet formation affect the final properties of super-Earth planets within the inner disk, comparing our mock-observed results to each other, as well as to the Kepler sample. We test several models of pebble accretion isolation mass, including pebble isolation, flow isolation, and migration feedback isolation and otherwise adopt the same parameters for the gas disk. We find that while each model can match at least one distribution of observables in the Kepler catalog, they fall short of matching all distributions simultaneously, even with extreme reweighting. Our inability to match all observations suggests that the initial conditions and/or modeled effects in our simulations that we held fixed should be investigated. This exploration sheds light on how planetary systems evolve and the processes that influence the wide range of system parameters we observe today, helping place our own Solar System in context.