APC - Universite' Paris Diderot and JPL - California Institute of Technology

We will present the SZ-richness scaling relation from Planck observations of more than 13,000 maxBCG clusters. By binning our SZ measurements, we detect the SZ signal down to the poorest systems in the catalog with high significance. We find that the SZ-richness relation is well-described by a power law over the entire richness range. The observed relation has a lower normalization than expected based on weak lensing mass estimates and the X-ray-based SZ-mass relation. Intriguingly, an X-ray subsample matches the model predictions notably better, and the SZ-X-ray luminosity relation remains consistent with X-ray model predictions.