Neptune's Migration into a Stirred-Up Kuiper Belt: A Detailed Comparison of Simulations to Observations

Nbody simulations are used to examine the consequences of Neptune's outwardmigration into the Kuiper Belt, with the simulated endstates being comparedrigorously and quantitatively to the observations. These simulations confirmthe findings of Chiang et al. (2003), who showed that Neptune's migration intoa previously stirred-up Kuiper Belt can account for the Kuiper Belt Objects(KBOs) known to librate at Neptune's 5:2 resonance. We also find that captureis possible at many other weak, high-order mean motion resonances, such as the11:6, 13:7, 13:6, 9:4, 7:3, 12:5, 8:3, 3:1, 7:2, and the 4:1. The more distantof these resonances, such as the 9:4, 7:3, 5:2, and the 3:1, can also captureparticles in stable, eccentric orbits beyond 50 AU, in the region of phasespace conventionally known as the Scattered Disk. Indeed, 90% of the simulatedparticles that persist over the age of the Solar System in the so-calledScattered Disk zone never had a close encounter with Neptune, but instead werepromoted into these eccentric orbits by Neptune's resonances during themigration epoch. This indicates that the observed Scattered Disk might not beso scattered. This model also produced only a handful of Centaurs, all of whichoriginated at Neptune's mean motion resonances in the Kuiper Belt. We alsoreport estimates of the abundances and masses of the Belt's varioussubpopulations (e.g., the resonant KBOs, the Main Belt, and the so-calledScattered Disk), and also provide upper limits on the abundance of Centaurs andNeptune's Trojans, as well as upper limits on the sizes and abundances ofhypothetical KBOs that might inhabit the a>50 AU zone.Comment: 60 pages, 16 figures. Accepted for publication in the Astronomical Journa