60 MICRON LUMINOSITY EVOLUTION OF RICH CLUSTERS OF GALAXIES

The average 60 μm flux has been determined for a collection of optically selected galaxy clusters at redshifts ranging from 0.30 to 0.92. The result, 26 mJy per cluster, represents the faintest flux determination we know of using the IRAS data base. The flux from this set of clusters has been compared to the 60 μm flux from a sample of nearby galaxy clusters. We find that the far-infrared luminosity evolution in cluster galaxies can be no more than a factor of 1.7 from z = 0.4 to the present epoch. This upper limit is close to the evolution predicted for simple aging of the stellar populations. Additional processes such as mergers, cannibalism, or enhanced rates of starbursts appear to occur at a low enough level that they have little influence on the farinfrared emission from clusters over this redshift range.