  We present a detailed investigation of the incidence of circumnuclear dust
structure in a large, well-matched sample of early-type galaxies with and
without Active Galactic Nuclei (AGN). All 34 early-type AGN hosts in our sample
have circumnuclear dust, while dust is only observed in 26% (nine) of a
pair-matched sample of 34 early-type, inactive galaxies. This result
demonstrates a strong correlation between the presence of circumnuclear dust
and accretion onto the central, supermassive black hole in elliptical and
lenticular galaxies. This correlation is not present at later Hubble types,
where a sample of 31 active and 31 inactive galaxies all contain circumnuclear
dust. These archival, HST observations reveal a wide range of mostly chaotic
dust morphologies. Current estimates suggest the dust settling or destruction
time is on order of 10^8 years and therefore the presence of dust in ~ 50% of
early-type galaxies requires frequent replenishment and similarly frequent
fueling of their central, supermassive black holes. The observed dust could be
internally-produced (via stellar winds) or externally-accreted, although there
are observational challenges for both of these scenarios. Our analysis also
reveals that approximately a third of the early-type galaxies without
circumnuclear dust have nuclear stellar disks. These nuclear stellar disks may
provide a preferred kinematic axis to externally-accreted material and this
material may in turn form new stars in these disks. The observed incidence of
nuclear stellar disks and circumnuclear dust suggests that episodic
replenishment of nuclear stellar disks occurs and is approximately concurrent
with the fueling of the central AGN.
