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We conduct a deep mid-infrared census of nine massive galaxy clusters at(0<z<1.3) with a total of ~1500 spectroscopically confirmed member galaxiesusing Spitzer/IRAC photometry and established mid-infrared color selectiontechniques. Of the 949 cluster galaxies that are detected in at least three ofthe four IRAC channels at the >3 sigma level, we identify 12 that hostmid-infrared selected active galactic nuclei (IR-AGN). To compare the IR-AGNacross our redshift range, we define two complete samples of cluster galaxies:(1) optically-selected members with rest-frame V(AB) magnitude <-21.5 and (2)mid-IR selected members brighter than (M*+0.5), i.e. essentially a stellar masscut. In both samples, we measure \agnfrac ~1% with a strong upper limit of ~3%at z<1. This uniformly low IR-AGN fraction at z<1 is surprising given thefraction of 24 micron sources in the same galaxy clusters is observed toincrease by about a factor of four from z~0 to z~1; this indicates that most ofthe detected 24 micron flux is due to star formation. Only in our single galaxycluster at z=1.24 is the IR-AGN fraction measurably higher at ~15% (allmembers; ~70% for late-types only). In agreement with recent studies, we findthe cluster IR-AGN are predominantly hosted by late-type galaxies with blueoptical colors, i.e. members with recent/ongoing star formation. The fourbrightest IR-AGN are also X-ray sources; these IR+X-ray AGN all lie outside thecluster core (Rproj>0.5 Mpc) and are hosted by highly morphologically disturbedmembers. Although our sample is limited, our results suggest that \agnfrac inmassive galaxy clusters is not strongly correlated with star formation at z<1,and that IR-AGN have a more prominent role at z>1.

A Census of Mid-Infrared Selected Active Galactic Nuclei in Massive Galaxy Clusters at 0 < z < 1.3