The Population of Kilometer-scale Retrograde Jovian Irregular Moons

TL;DR

This study used archival telescope data to identify and estimate the population of small, kilometer-scale irregular moons around Jupiter, revealing approximately 600 such moons and characterizing their size distribution.

Contribution

It provides the first estimate of the population of km-scale irregular moons around Jupiter and details their size distribution down to 400 meters radius.

Findings

Detected 52 irregular moons in archival data.

Estimated total population of >0.4 km moons as approximately 600.

Found a shallow luminosity function with an exponential index of 0.29.

Abstract

We have searched a 2010 archival data set from the Canada-France-Hawaii Telescope for very small (km-scale) irregular moons of Jupiter in order to constrain the size distribution of these moons down to radii of $\sim 400$~m, discovering 52 objects which are moving with Jupiter-like on-sky rates and are nearly certainly irregular moons. The four brightest detections, and seven in total, were all then linked to known jovian moons. Extrapolating our characterized detections (those down to magnitude $m_r=25.7$) to the entire retrograde circum-jovian population, we estimate the population of radius $>0.4$~km moons to be 600 (within a factor of 2). At the faintest magnitudes we find a relatively shallow luminosity function of exponential index $\alpha= 0.29 \pm 0.15$, corresponding to a differential diameter power law of index $q\simeq 2.5$.