Modelling galaxy cluster triaxiality in stacked cluster weak lensing analyses

ABSTRACT Counts of galaxy clusters offer a high-precision probe cosmology, but control systematic errors will determine the accuracy this measurement. Using Buzzard simulations, we quantify one such systematic, triaxiality distribution identified with redMaPPer optical cluster finding algorithm, which was used in Dark Energy Survey Year-1 (DES Y1) cosmology analysis. We test whether selection biases clusters’ shape and orientation find that it only orientation, preferentially selecting their major axes oriented along line sight. Modelling richness–mass relation as log-linear, log-richness amplitude ln (A) is boosted from lowest to highest bin significance 14σ, while dependence richness-mass slope intrinsic scatter minimal. also weak lensing shear-profile ratios cluster-associated dark haloes different bins resemble ‘bottleneck’ can be quantified Cauchy function. correlation two other leading systematics – miscentering projection null correlation. The resulting mass bias predicted our templates confirms DES Y1 source cosmology. However, richness-dependence does not fully resolve tension at low-richness between probes. Our model for quantifying impact on cosmological constraints upcoming surveys clusters.