Impact of Systematics on SZ-Optical Scaling Relations

TL;DR

This paper investigates how systematic uncertainties in optical galaxy cluster catalogs affect the stacked Sunyaev-Zel'dovich (SZ) signals, revealing significant variations and biases that influence cosmological inferences.

Contribution

It quantifies the impact of optical catalog systematics on SZ measurements and demonstrates consistency with Planck data when these uncertainties are considered.

Findings

Optical systematic uncertainties can cause up to 50% variation in predicted SZ signals.

Mis-centering and impurities lead to signal suppression, but less than other systematics.

X-ray based sub-sampling introduces Malmquist bias, increasing observed SZ signals.

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 SZ signals. We show that the optically predicted Y-decrement can vary by as much as 50% based on the current 2 sigma systematic uncertainties in the observed mass-richness relationship. Mis-centering 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 level of these variations and suppression is 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 SDSS optical clusters and their X-ray counterparts are consistent with expectations after accounting for the 1 sigma optical systematic uncertainties using the Johnston mass richness relation.