2009ApJ...695.1191K

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 µm and 160 µm 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 2σ upper limits on the excess emission within 100 kpc of the cluster center as 5x10^–3 MJy/sr, 6x10^–2 MJy/sr, and 7x10^–2 MJy/sr, at 24, 70, and 160 µm, 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 with the interstellar medium.