Weak Lensing Measurement of the Mass--Richness Relation of SDSS redMaPPer Clusters

TL;DR

This study accurately measures the mass--richness relation of SDSS redMaPPer galaxy clusters using weak lensing, thoroughly accounting for systematic uncertainties to provide a definitive calibration.

Contribution

It presents the first comprehensive systematic uncertainty analysis for weak lensing mass calibration of SDSS redMaPPer clusters, establishing a precise mass--richness relation.

Findings

Mass--richness relation normalization: log10[M200m/h^{-1} M_sun] = 14.344 ± 0.021 (stat) ± 0.023 (sys).

Power-law index of the relation: 1.33^{+0.09}_{-0.10}.

Calibration uncertainty of 7% in the mass normalization.

Abstract

We perform a measurement of the mass--richness relation of the redMaPPer galaxy cluster catalogue using weak lensing data from the Sloan Digital Sky Survey. We have carefully characterized a broad range of systematic uncertainties, including shear calibration errors, photo-$z$ biases, dilution by member galaxies, source obscuration, magnification bias, incorrect assumptions about cluster mass profiles, cluster centering, halo triaxiality, and projection effects. We also compare measurements of the lensing signal from two independently-produced shear and photometric redshift catalogues to characterize systematic errors in the lensing signal itself. Using a sample of 5,570 clusters from $0.1\le z\le 0.33$, the normalization of our power-law mass vs.\ $\lambda$ relation is $\log_{10}[M_{200m}/h^{-1}\ M_{\odot}]$ = $14.344 \pm 0.021$ (statistical) $\pm 0.023$ (systematic) at a richness $\lambda=40$, a 7 per cent calibration uncertainty, with a power-law index of $1.33^{+0.09}_{-0.10}$ ($1\sigma$). The detailed systematics characterization in this work renders it the definitive weak lensing mass calibration for SDSS redMaPPer clusters at this time.