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Detection of a divot in the size distribution of the Kuiper Belt's scattering objects

University of British Columbia

We present a joint analysis of the Canada France Ecliptic Plane Survey's scattering objects, and the Kaib et al. (2011b) orbital model, measuring the scattering objects' size distribution. Scattering objects are Trans-Neptunian objects which are strongly interacting with Neptune, having scattering encounters which change their semimajor axes on short dynamical timescales. We reject a single power-law distribution at the 99% level, and find that a dearth of small objects is required. We present a novel parameterisation of a divot size distribution, which rises as a single power-law to a precipitous drop, then recovers as another single power-law of potentially different slope. We constrain the form of such a divot distribution, and find that divots are preferred over "knee" size distributions, which are found elsewhere in the literature for different populations. We present our preferred divot scenario, which rises as a single power-law of logarithmic slope α = 0.8 as absolute Hg magnitudes increase to sizes corresponding to D ~ 100 km, then dropping by a factor of about 6 in differential number, followed by another single power-law of logarithmic slope α = 0.5. Our interpretation is that this feature arose from the size distribution made by planetesimal formation and is now "frozen in" to the "hot" populations of the outer Solar System. From this we estimate there are 2‧10⁹ scattering objects with Hg < 18, allowing for enough to supply the nearby Jupiter Family comets. This interpretation nicely ties the "hot" populations together while simultaneously explaining the source of the Jupiter Family comets and the observed paucity of intermediate-sized (50-100 km) Neptune Trojans.

Text

2012-08-24

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/43043

Astronomy

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/