SZ Scaling Relations of Galaxy Groups and Clusters Near the North Ecliptic Pole

Abstract

Sunyaev–Zel’dovich (SZ) scaling relations have been used to test the self-similar prediction for massive galaxy clusters, but little attention has been given to individual galaxy groups. We investigate the scaling relations of galaxy groups and clusters near the North Ecliptic Pole using X-ray and SZ observations. This region of the sky is where both the ROSAT and Planck satellites achieved their deepest observations, permitting the investigation of lower mass systems. Our sample consists of 62 X-ray detected groups and clusters, spanning a mass range of and redshifts of 0.03 ≲  z  ≲ 0.82. We extract the total SZ flux from unresolved Planck data and estimate the fraction of the SZ flux within R 500 assuming two different pressure profiles. The SZ scaling relations were derived using a Bayesian technique that accounts for censored data. We find a power law slope of for the Y SZ – M 500 relation that is consistent with the self-similar prediction of 5/3. The slope of for the relation is in agreement with other observational studies but not the self-similar prediction of 5/4, and the relation lies below the 1:1 relation when the slope is fixed to unity. The determined scaling relations are dependent on the selected pressure profile, so resolved data are needed to determine the effects of active galactic nucleus feedback. In addition, we find a number of potential cluster candidates in the Planck Compton maps that were not identified in our X-ray sample.