Gravity-selected cluster samples: a new take on the Compton Y-mass relation

TL;DR

This study examines the relation between the Compton Y parameter and galaxy cluster mass using a gravity-selected sample, revealing greater scatter and a second cluster population not seen in ICM-selected samples.

Contribution

It introduces a gravity-selected cluster sample to analyze the Y-mass relation, avoiding biases inherent in ICM-selected samples and identifying a new cluster population.

Findings

Broader scatter in Y-mass relation compared to ICM-selected samples.

Identification of a second population with low Y for their mass.

Approximately 13% of clusters belong to this second population.

Abstract

We investigate the scaling relation between the Compton Y parameter and mass in a gravity-selected sample of galaxy clusters, selected based on their gravitational lensing effects on background galaxies. Unlike ICM-selected samples, gravity-selected clusters do not require corrections for selection biases in intracluster medium (ICM) properties, such as Compton Y, since these properties are not used for selection. Our sample consists of 13 gravity-selected clusters with weak-lensing signal-to-noise ratios greater than 7 and redshifts in the range $0.1 < z < 0.4$, drawn from the peak catalog of shear-selected clusters in Oguri et al. (2021). We determined spectroscopic redshifts using SDSS spectroscopy, derived tangential radial profiles from HSC shear data, and calculated cluster masses by fitting a Navarro, Frenk, \& White (1997) profile. Compton Y measurements were obtained from ACT maps. Our sample reveals a broader scatter in the Compton Y-mass scaling relation compared to ICM-selected samples, even after accounting for selection effects and mass bias of the latter, that we find to be $(1-b) = 0.72 \pm 0.09$. Additionally, we identify a second population of clusters with unusually small Compton Y for their mass, which is absent in ICM-selected samples. This second population comprises $13^{+10}_{-8}$\% of the entire sample, with O19 currently being the only secure representative.