Infrared-red Cores in Nearby Elliptical Galaxies
  We present the Spitzer Space Telescope Infrared Array Camera (IRAC)
observations for a sample of local elliptical galaxies to study later stages of
AGN activities. A sample of 36 elliptical galaxies is selected from the Palomar
spectroscopic survey. We detect nuclear non-stellar infrared emission in 9 of
them. There is unambiguous evidence of circumnuclear dust in these 9 galaxies
in their optical images. We also find a remarkable correlation between the
infrared excess emission and the nuclear radio/X-ray emission, suggesting that
infrared excess emission is tightly related with nuclear activity. Possible
origin of infrared excess emission from hot dust heated by the central AGN is
supported by spectral indices of IR excess emission.
