A single sub-km Kuiper Belt object from a stellar Occultation in archival data

TL;DR

This study analyzes archival data to detect a 500-meter Kuiper Belt object via stellar occultation, revealing a scarcity of sub-kilometer KBOs and supporting the idea of collisional erosion in the Kuiper Belt.

Contribution

It provides the first confirmed detection of a sub-km KBO from archival data and constrains the size distribution, challenging previous higher estimates.

Findings

Detected a 500 m radius KBO at 45 AU with 2% probability of chance occurrence.

Ruling out previous claims, the surface density of sub-km KBOs is significantly lower than expected.

Evidence supports collisional erosion as a key process shaping the small KBO population.

Abstract

The Kuiper belt is a remnant of the primordial Solar System. Measurements of its size distribution constrain its accretion and collisional history, and the importance of material strength of Kuiper belt objects (KBOs). Small, sub-km sized, KBOs elude direct detection, but the signature of their occultations of background stars should be detectable. Observations at both optical and X-ray wavelengths claim to have detected such occultations, but their implied KBO abundances are inconsistent with each other and far exceed theoretical expectations. Here, we report an analysis of archival data that reveals an occultation by a body with a 500 m radius at a distance of 45 AU. The probability of this event to occur due to random statistical fluctuations within our data set is about 2%. Our survey yields a surface density of KBOs with radii larger than 250 m of 2.1^{+4.8}_{-1.7} x 10^7 deg^{-2}, ruling out inferred surface densities from previous claimed detections by more than 5 sigma. The fact that we detected only one event, firmly shows a deficit of sub-km sized KBOs compared to a population extrapolated from objects with r>50 km. This implies that sub-km sized KBOs are undergoing collisional erosion, just like debris disks observed around other stars.