Influence of cold Jupiters in the formation of close-in planets

The formation of a cold Jupiter (CJ) is expected to quench the influx of pebbles and the migration of cores interior to its orbit, thus limiting the efficiency of inner rocky planet formation either by pebble accretion and/or orbital migration. Observations, however, show that the presence of outer CJs ( > 1 au and > 0.3M_J ) correlates that of inner Super Earths ( < 1 au). This observation may simply be a result of an enhanced initial reservoir of solids in the nebula required to form a CJ or a yet-to-determined mechanism assisted by the presence of a CJ.

In this work, we focus on the latter alternative and study the orbital transport of planetesimals interior to a CJ subject to the gravity and drag from a viscously-evolving gaseous disk. We find that a secular resonance sweeping inwards through the disk gradually transports rings of planetesimals when their drag-assisted orbital decay is faster than the speed of the moving resonance. This snowplow-like process leads to large concentration (boosted by a factor of ∼10−100) of size-segregated planetesimal rings with aligned apsidal lines, making their expected collisions less destructive due to their reduced relative velocities. This process is efficient for a wide range of α−disk models and Jovian masses, peaking for ∼1−5M_J , typical of observed CJs in radial velocity surveys.

Overall, our work shows the major role of the disk’s gravity in the redistribution of planetesimals and depicts a novel venue by which CJs may enhance the formation of inner planetary systems.