Debiased Populations of Kuiper Belt Objects from the Deep Ecliptic Survey
Abstract
The Deep Ecliptic Survey (DES) was a survey project that discovered hundreds of Kuiper Belt objects from 1998 to 2005. Extensive followup observations of these bodies has yielded 304 objects with welldetermined orbits and dynamical classifications into one of several categories: Classical, Scattered, Centaur, or 16 meanmotion resonances with Neptune. The DES search fields are well documented, enabling us to calculate the probability on each frame of detecting an object with its particular orbital parameters and absolute magnitude at a randomized point in its orbit. The detection probabilities range from a maximum of 0.32 for the 3:2 resonant object 2002 GF _{32} to a minimum of 1.5 × 10^{7} for the faint Scattered object 2001 FU _{185}. By grouping individual objects together by dynamical classes, we can estimate the distributions of four parameters that define each class: semimajor axis, eccentricity, inclination, and object size. The orbital element distributions (a, e, and i) were fit to the largest three classes (Classical, 3:2, and Scattered) using a maximum likelihood fit. Using the absolute magnitude (H magnitude) as a proxy for the object size, we fit a power law to the number of objects versus H magnitude for eight classes with at least five detected members (246 objects). The Classical objects are best fit with a powerlaw slope of α = 1.02 ± 0.01 (observed from 5 <= H <= 7.2). Six other dynamical classes (Scattered plus five resonances) have consistent magnitude distribution slopes with the Classicals, provided that the absolute number of objects is scaled. Scattered objects are somewhat more numerous than Classical objects, while there are only a quarter as many 3:2 objects as Classicals. The exception to the power law relation is the Centaurs, which are nonresonant objects with perihelia closer than Neptune and therefore brighter and detectable at smaller sizes. Centaurs were observed from 7.5 < H < 11, and that population is best fit by a power law with α = 0.42 ± 0.02. This is consistent with a knee in the Hdistribution around H = 7.2 as reported elsewhere. Based on the Classicalderived magnitude distribution, the total number of objects (H <= 7) in each class is: Classical (2100 ± 300 objects), Scattered (2800 ± 400), 3:2 (570 ± 80), 2:1 (400 ± 50), 5:2 (270 ± 40), 7:4 (69 ± 9), 5:3 (60 ± 8). The independent estimate for the number of Centaurs in the same H range is 13 ± 5. If instead all objects are divided by inclination into "Hot" and "Cold" populations, following Fraser et al., we find that α_{Hot} = 0.90 ± 0.02, while α_{Cold} = 1.32 ± 0.02, in good agreement with that work.
 Publication:

The Astronomical Journal
 Pub Date:
 September 2014
 DOI:
 10.1088/00046256/148/3/55
 arXiv:
 arXiv:1311.3250
 Bibcode:
 2014AJ....148...55A
 Keywords:

 Kuiper belt: general;
 methods: data analysis;
 planets and satellites: formation;
 planets and satellites: general;
 surveys;
 Astrophysics  Earth and Planetary Astrophysics
 EPrint:
 26 pages emulateapj, 6 figures, 5 tables, accepted by AJ