Impact of Systematics on SZ-Optical Scaling Relations

Abstract

One of the central goals of multi-wavelength galaxy cluster cosmology is to unite all cluster observables to form a consistent understanding of cluster mass. Here, we study the impact of systematic effects from optical cluster catalogs on stacked Sunyaev-Zel'dovich (SZ) signals. We show that the optically predicted Y -decrement can vary by as much as 50% based on the current 2σ systematic uncertainties in the observed mass-richness relationship. Miscentering and impurities will suppress the SZ signal compared to expectations for a clean and perfectly centered optical sample, but to a lesser degree. We show that the levels of these variations and suppression are dependent on the amount of systematics in the optical cluster catalogs. We also study X-ray luminosity-dependent sub-sampling of the optical catalog and find that it creates Malmquist bias, increasing the observed Y -decrement of the stacked signal. We show that the current Planck measurements of the Y -decrement around Sloan Digital Sky Survey optical clusters and their X-ray counterparts are consistent with expectations after accounting for the 1σ optical systematic uncertainties using the Johnston mass-richness relation.