Infrared Emission from Intracluster Dust Grains and Constraints on Dust Properties

Abstract

For 117 clusters of galaxies, we explore the detectability of intracluster dust grains by current and future infrared facilities, taking into account both collisional heating and sputtering of grains by ambient plasma. If the dust grains are injected into the intergalactic space with the amount and size comparable to the Galactic values, the dust-to-gas ratio is typically $10^{-6}$ and the mean dust temperature is $\sim 30$ K near the cluster center. The predicted infrared intensities lie marginally above the detection thresholds for Spitzer Space Telescope, ASTRO-F, Herschel and SPICA missions. For some nearby clusters such as Perseus, A3571, A2319, A3112 and A2204, good detections of intracluster dust signal are expected in the 70 $μ$m band. Given rather tight constraints on the dust temperature from observed electron density and temperature, the dust mass can be inferred directly from the infrared observations. Further constraints on the size distribution will be obtained once multi-band data are available. They will definitely provide a powerful probe of the dust injection processes and dust-gas interactions in the intergalactic space.