Constraints on the Intracluster Dust Emission in the Coma Cluster of
  Galaxies
  We have undertaken a search for the infrared emission from the intracluster
dust in the Coma cluster of galaxies by the Multiband Imaging Photometer for
Spitzer. Our observations yield the deepest mid and far-infrared images of a
galaxy cluster ever achieved. In each of the three bands, we have not detected
a signature of the central excess component in contrast to the previous report
on the detection by Infrared Space Observatory (ISO). We still find that the
brightness ratio between 70 and 160 microns shows a marginal sign of the
central excess, in qualitative agreement with the ISO result. Our analysis
suggests that the excess ratio is more likely due to faint infrared sources
lying on fluctuating cirrus foreground. Our observations yield the 2 sigma
upper limits on the excess emission within 100 kpc of the cluster center as 5 x
10^-3 MJy/sr, 6 x 10^-2 MJy/sr, and 7 x 10^-2 MJy/sr, at 24, 70, and 160
microns, respectively. These values are in agreement with those found in other
galaxy clusters and suggest that dust is deficient near the cluster center by
more than 3 orders of magnitude compared to the interstellar medium.
