Title:  Hot Jupiters are not as lonely as we thought

Abstract:  The first discovered extrasolar worlds -- giant, ``hot Jupiter'' planets orbiting remarkably close to their parent stars -- came as a surprise to solar-system-centric models of planet formation, prompting the development of new theories to produce these unexpected planets. The striking dearth of observed nearby planetary companions to hot Jupiters has been widely quoted as evidence in support of high-eccentricity tidal migration: a framework in which hot Jupiters form further out in their natal protoplanetary disks before being thrown inward via violent high-eccentricity tidal migration, stripping systems of any close-in planetary companions. By contrast, we present evidence that nearby planetary companions to hot Jupiters are far more common than previously thought. We demonstrate through an analysis of the full four-year Kepler dataset that at minimum 15% of hot Jupiters have a nearby planetary companion. This subset of hot Jupiters must have a quiescent formation history such that they were able to retain nearby companions. Furthermore, we demonstrate a ubiquity of nearby planetary companions to warm Jupiters, indicating that warm Jupiters typically form quiescently. We conclude with a new paradigm for producing short-period gas giants that is consistent with all current lines of evidence, in which at least ~15% of hot Jupiters form in situ and the other ~85% undergo high-eccentricity migration.

Host:  Dan Stevens

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