Sunyaev-Zel'dovich signal of the maxBCG SDSS galaxy clusters in WMAP

The Planck Collaboration measured the Sunyaev-Zel'dovich decrement of optically selected clusters from the Sloan Digital Sky Survey, finding that it falls significantly below expectations based on existing mass calibration of the maxBCG galaxy clusters. Resolving this tension requires either the data to go up, or the theoretical expectations to come down. Here, we use data from the Wilkinson Microwave Anisotropy Probe to perform an independent estimate of the Sunyaev-Zel'dovich decrement of maxBCG clusters. The recovered signal is consistent with that obtained using the Planck satellite, though with larger error bars due to the Wilkinson Microwave Anisotropy Probe's larger beam size and smaller frequency range. Nevertheless, this detection serves as an independent confirmation of the magnitude of the effect, and demonstrates that the observed discrepancy must originate in modeling or other systematic uncertainties.