CoMaLit -- VI. Intrinsic scatter in stacked relations. The weak lensing AMICO galaxy clusters in KiDS-DR3

TL;DR

This paper introduces a Bayesian method to measure the intrinsic scatter in stacked weak lensing analyses, improving mass estimates of galaxy clusters from optical richness with high precision.

Contribution

It presents a novel Bayesian approach to constrain the intrinsic scatter in stacked weak lensing measurements, enhancing cluster mass calibration accuracy.

Findings

Optical richness is confirmed as a low scatter mass proxy.

Mass of individual clusters can be estimated with ~20% precision.

Method applied to KiDS-DR3 data with successful results.

Abstract

Unbiased and precise mass calibration of galaxy clusters is crucial to fully exploit galaxy clusters as cosmological probes. Stacking of weak lensing signal allows us to measure observable-mass relations down to less massive halos halos without extrapolation. We propose a Bayesian inference method to constrain the intrinsic scatter of the mass proxy in stacked analyses. The scatter of the stacked data is rescaled with respect to the individual scatter based on the number of binned clusters. We apply this method to the galaxy clusters detected with the AMICO (Adaptive Matched Identifier of Clustered Objects) algorithm in the third data release of the Kilo-Degree Survey. The results confirm the optical richness as a low scatter mass proxy. Based on the optical richness and the calibrated weak lensing mass-richness relation, mass of individual objects down to ~10^13 solar masses can be estimated with a precision of ~20 per cent.