We conducted a two-night photometric survey of small Kuiper Belt objects
(KBOs) near opposition using the wide-field Hyper Suprime-Cam instrument on the
8.2 m Subaru Telescope. The survey covered about 90 deg^2 of sky, with each
field imaged in the g and i bands. We detected 356 KBOs, ranging in absolute
magnitude from 6.5 to 10.4. Filtering for high-inclination objects within the
hot KBO population, we show that the g-i color distribution is strongly
bimodal, indicative of two color classes - the red and very red subpopulations.
After categorizing objects into the two subpopulations by color, we present the
first dedicated analysis of the magnitude distributions of the individual color
subpopulations and demonstrate that the two distributions are roughly identical
in shape throughout the entire size range covered by our survey. Comparing the
color distribution of small hot KBOs with that of Centaurs, we find that they
have similar bimodal shapes, thereby providing strong confirmation of previous
explanations for the attested bimodality of Centaurs. We also show that the
magnitude distributions of the two KBO color subpopulations and the two color
subpopulations observed in the Jupiter Trojans are statistically
indistinguishable. Finally, we discuss a hypothesis describing the origin of
the KBO color bimodality based on our survey results.Comment: 9 pages, 6 figures, accepted for publication in AJ, supplemental
table accessible on online journa
