Ossos. Ii. A Sharp Transition in the Absolute Magnitude Distribution of the Kuiper Belt’s Scattering Population

Abstract

We measure the absolute magnitude, H, distribution, dN(H)∝10αH , of the scattering Trans-Neptunian Objects (TNOs) as a proxy for their size-frequency distribution. We show that the H-distribution of the scattering TNOs is not consistent with a single-slope distribution, but must transition around H g ∼9 to either a knee with a shallow slope or to a divot, which is a differential drop followed by second exponential distribution. Our analysis is based on a sample of 22 scattering TNOs drawn from three different TNO surveys-the Canada-France Ecliptic Plane Survey, Alexandersen et al., and the Outer Solar System Origins Survey, all of which provide well-characterized detection thresholds-combined with a cosmogonic model for the formation of the scattering TNO population. Our measured absolute magnitude distribution result is independent of the choice of cosmogonic model. Based on our analysis, we estimate that the number of scattering TNOs is (2.4-8.3)×105 for H r <12. A divot H-distribution is seen in a variety of formation scenarios and may explain several puzzles in Kuiper Belt science. We find that a divot H-distribution simultaneously explains the observed scattering TNO, Neptune Trojan, Plutino, and Centaur H-distributions while simultaneously predicting a large enough scattering TNO population to act as the sole supply of the Jupiter-Family Comets.

Ossos Iii—resonant Trans-Neptunian Populations: Constraints From the First Quarter of the Outer Solar System Origins Survey

“…Recently, Fraser et al (2014) found that these populations can be modeled by a broken exponential H distribution with a bright end slope α = 0.9 that breaks to a faint end slope α ∼ 0.2 at H r (break) ∼ 8. Shankman et al (2013Shankman et al ( , 2016 find that the scattering population shows evidence of a divot (a deficit of objects rather than a simple change in slope) in the H distribution near H g ∼ 9, corresponding to H r ∼ 8. 4.…”

OSSOS. V. Diffusion in the Orbit of a High-perihelion Distant Solar System Object

“…The particles were given orbits from uniform 100<a< 1000 au, 45<q<100 au distributions, with an isotropic inclination distribution from 0°to 20°P(i)∝sin(i), and random distributions of other angles. We drew H magnitudes with H r  8 (recalling H SY99 = 6.8) from a single slope of α=0.9, as is consistent with the observed hot and scattering TNO distributions, prior to the transition to an undetermined form past H r =8 (Fraser et al 2014;Shankman et al 2016). The simulated detections, shown in Figure 3, are evenly detected at inclinations 3<i<20°, dropping at i<3°.…”

“…Figure 2 (top) shows the tide-free evolution of 60 clones of 2013 SY 99 for 4 Gyr in a 0.5 year time step with the hybrid symplectic/Bulirsch-Stoer algorithm in MER-CURY6 (Chambers 1999). As in Shankman et al (2016), three clusters each of 20 clones were generated, at the (a, q) extremes and at the nominal orbit, per the orbital uncertainties in Table 1. Particles were removed if they reached a> 10,000 au; this happened to one out of the 60 total clones.…”

The Bimodal Color Distribution of Small Kuiper Belt Objects*

“…The magnitude distribution of KBOs has been the subject of intensive study over the past decade, with numerous dedicated surveys having been undertaken to explore the shape of the distribution through H 11 12 = -. Many recent published works in the literature present incompleteness-corrected KBO magnitude distributions extending well beyond the completeness limit of our photometric survey (e.g., Fraser et al 2014;Shankman & Kavelaars 2016).…”