Effects of Outer Giant Planets on In Situ Formation of Inner Super-Earths

Abstract

Recent studies have found an observational correlation between the presence of outer giant planets and inner super-Earths, which implies that outer giants do not suppress the formation of super-Earths. We simulate late-stage in situ planet formation in the presence of outer giant planets using $N$-body simulations. We investigate the effects of two sets of outer giants: the four Solar System giant planets and three dynamically active giant planets. Compared to systems without outer giants, we find that systems with the Solar System giants tend to form inner super-Earths that are more compact, coplanar, and circular, while the systems with the dynamically active giants form inner super-Earths that are more eccentric, inclined, and widely spaced, with lower intrinsic multiplicity. Including a contribution from systems that form with dynamically active giant planets allows us to match observable quantities of super-Earths, including their two component eccentricity distribution. However, matching the observed population requires different formation conditions prior to the giant impact stage for systems with vs. without giant planets. In our model, observed super-Earths that form in the presence of dynamically active outer giants emerge from disks with lower solid surface densities and without a depleted gas stage, suggesting that the giant planets may have reduced, but not prevented, delivery and/or accretion of solids in the inner disk. With a large enough sample of inner and outer systems, we could break down occurrence rates of inner super-Earths based on the properties of outer giants, and vice versa, and then compare these conditional probabilities with simulations.

24 pages, 15 figures, published in ApJ

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