SPITZER/MIPS 24 μm OBSERVATIONS OF GALAXY CLUSTERS: AN INCREASING FRACTION OF OBSCURED STAR-FORMING MEMBERS FROM z=0.02 TO z=0.83

We study the mid-infrared properties of 1315 spectroscopically confirmed members in eight massive (M(vir) greater than or similar to 5 X 10(14) M(circle dot)) galaxy clusters covering the redshift range from 0.02 to 0.83. The selected clusters all have deep Spitzer/MIPS 24 mu m observations, Hubble and ground-based photometry, and extensive redshift catalogs. We observe for the first time an increase in the fraction of cluster galaxies with mid-infrared star formation rates higher than 5 M(circle dot) yr(-1) from 3% at z = 0.02 to 13% at z = 0.83 R(p) <= 1 Mpc). This increase is reproduced even when considering only the most massive members (M(*) >= 4 x 10(10) M(circle dot)). The 24 mu m observations reveal stronger evolution in the fraction of blue/star-forming cluster galaxies than in color-selected samples: the number of dusty, strongly star-forming cluster galaxies increases with redshift, and combining these with the optically defined Butcher-Oemler members [Delta(B - V) < - 0.2] doubles the total fraction of blue/star-forming galaxies in the inner Mpc of the clusters to similar to 23% at z = 0.83. These results, the first of our Spitzer/MIPS Infra-Red Cluster Survey (SMIRCS), support earlier studies indicating that the increase in star-forming members is driven by cluster assembly and galaxy infall, as is expected in the framework of hierarchical formation.