Dust evolution with active galactic nucleus feedback in elliptical
  galaxies
  We have recently suggested that dust growth in the cold gas phase dominates
the dust abundance in elliptical galaxies while dust is efficiently destroyed
in the hot X-ray emitting plasma (hot gas). In order to understand the dust
evolution in elliptical galaxies, we construct a simple model that includes
dust growth in the cold gas and dust destruction in the hot gas. We also take
into account the effect of mass exchange between these two gas components
induced by active galactic nucleus (AGN) feedback. We survey reasonable ranges
of the relevant parameters in the model and find that AGN feedback cycles
actually produce a variety in cold gas mass and dust-to-gas ratio. By comparing
with an observational sample of nearby elliptical galaxies, we find that,
although the dust-to-gas ratio varies by an order of magnitude in our model,
the entire range of the observed dust-to-gas ratios is difficult to be
reproduced under a single parameter set. Variation of the dust growth
efficiency is the most probable solution to explain the large variety in
dust-to-gas ratio of the observational sample. Therefore, dust growth can play
a central role in creating the variation in dust-to-gas ratio through the AGN
feedback cycle and through the variation in dust growth efficiency.
