Physical Properties of the Asteroid Belts from Brightness-limited Surveys

We introduce a general debiasing Bayesian formalism to brightness-limited surveys of solar system objects that constrains the statistical distribution of a population’s physical characteristics such as size, albedo, heliocentric distance, or others to account for the survey detections and measured properties such as brightness. We reanalyze the Dark Energy Camera search for main-belt asteroids of Peña et al. and fit a smooth double power-law size to its size distribution. Using only detections with reliable distances and accurate orbital information, we find no evidence for a significant difference in size distribution between the inner, middle, and outer belts for objects between 0.1 and 1 km in diameter, with q 2 = 2.27 ± 0.05 a good fit for the small-end slope. We show that the intrinsic number density of objects is consistent between these populations and is compatible with observational biases. As spectral classes are distributed unevenly throughout the main belt, these results support the ongoing collisional reprocessing of the asteroid belt for objects smaller than 5 km.