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Debiasing surveys for physical characteristics of sparse populations, from Asteroid families to ISOs.

Presentation #113.04 in the session Asteroids: Observational Surveys (Oral Presentation)

Published onOct 23, 2023
Debiasing surveys for physical characteristics of sparse populations, from Asteroid families to ISOs.

We introduce a general de-biasing bayesian formalism to account for the physical characteristics of a subpopulation. The main observational bias is brightness which is severely affected by heliocentric distance. The distance distribution must be considered when determining properties like size, and albedo. This approach allows us to consider complex correlations between brightness and distance, like those expected for comets. We have applied it to a well calibrated brightness-limited asteroid survey, and shown its usefulness for other asteroid wide field surveys like WISE, and particularly for sparse populations with uncertain properties like Interstellar Objects (ISOs), or poorly constrained distance distributions like Centaurs.

We show our re-analysis of the Dark Energy Camera (DECam) search for main-belt asteroids (Pena, 2018) where for objects between 0.1 and 1 km in diameter we find no evidence for a significant difference in size distribution between the inner, middle, and outer belts. We further estimate the difference in numbers is consistent with observational biases, finding a slope of q~2.3 a good fit for the small-end size distribution slope. Our analysis is extended to the WISE/NEOWISE data, trying to de-bias intrinsic subpopulation properties, better determining differences between families.

This approach is notably useful when surveying populations with uncertain physical properties. We consider different statistical physical properties for the ISO population. By estimating the expected number of ISOs and possible different classes like IS-comets and IS-asteroids, we can compare them to Solar System populations. In the coming decade of large, and consistent all-sky surveys we show how the relative number of active Interstellar comets like 2I/Borisov compared to that of dormant asteroids like 1I/‘Oumuamua constrain their size distribution. This also allows for a direct comparison to local populations, like the Long Period Comets.

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