Collisional Grooming Models of the Kuiper Belt Dust Cloud

TL;DR

This study models the 3-D structure of the Kuiper Belt dust cloud, revealing how grain collisions and resonances shape its features across different dust production rates and optical depths.

Contribution

It introduces a collisional grooming model that incorporates grain-grain collisions and planet-dust interactions to simulate the Kuiper Belt dust structure.

Findings

A symmetric ring at 40-47 AU in high optical depth models.

Resonance trapping causes gaps and secondary rings at low optical depths.

Collisions erase azimuthal asymmetries in the dust disk.

Abstract

We modeled the 3-D structure of the Kuiper Belt dust cloud at four different dust production rates, incorporating both planet-dust interactions and grain-grain collisions using the collisional grooming algorithm. Simulated images of a model with a face-on optical depth of ~10^-4 primarily show an azimuthally-symmetric ring at 40-47 AU in submillimeter and infrared wavelengths; this ring is associated with the cold classical Kuiper Belt. For models with lower optical depths (10^-6 and 10^-7), synthetic infrared images show that the ring widens and a gap opens in the ring at the location of of Neptune; this feature is caused by trapping of dust grains in Neptune's mean motion resonances. At low optical depths, a secondary ring also appears associated with the hole cleared in the center of the disk by Saturn. Our simulations, which incorporate 25 different grain sizes, illustrate that grain-grain collisions are important in sculpting today's Kuiper Belt dust, and probably other aspects of the Solar System dust complex; collisions erase all signs of azimuthal asymmetry from the submillimeter image of the disk at every dust level we considered. The model images switch from being dominated by resonantly-trapped small grains ("transport dominated") to being dominated by the birth ring ("collision dominated") when the optical depth reaches a critical value of tau ~ v/c, where v is the local Keplerian speed.