2015ApJ...808...14M

Hot Jupiters are giant planets on orbits of a few hundredths of an AU. They do not share their system with low-mass close-in planets, despite the latter being exceedingly common. Two migration channels for hot Jupiters have been proposed: through a protoplanetary gas disk or by tidal circularization of highly eccentric planets. We show that highly eccentric giant planets that will become hot Jupiters clear out any low-mass inner planets in the system, explaining the observed lack of such companions to hot Jupiters. A less common outcome of the interaction is that the giant planet is ejected by the inner planets. Furthermore, the interaction can implant giant planets on moderately high eccentricities at semimajor axes AU, a region otherwise hard to populate. Our work supports the hypothesis that most hot Jupiters reached their current orbits following a phase of high eccentricity, possibly excited by other planetary or stellar companions.