Speaker
Zhuowen Zhang
Description
My talk summarizes the modeling of triaxiality on weak lensing galaxy cluster mass estimates for DES Y3 analysis. We use Buzzard dark matter halos and particle simulations to measure the shapes of halos and the redMaPPer algorithm to detect clusters to redshifts up to z < 0.90. We show that triaxiality biases the selection of the redMapper algorithm primarily as a bias in orientation, with a secondary selection effect on the ellipticity of selected halos. The selection bias presents itself observably as a shift in the richness-mass relation, which is best characterized by a linear relation with an upward shifted amplitude for halos orientated with their major axes toward the line of sight. In addition, the surface density shows a significant dependence with orientation in both the one halo and two halo regime, which can be well modeled by a Cauchy function fit. The orientation dependent template for the richness-mass relation and surface density, combined with the appropriate halo mass function for a given cosmology, outputs the stacked weak lensing cluster surface density that largely minimizes the systematics from triaxiality. Our model will largely reduce the systematics from triaxiality in the systematics-limited DES Y3 cosmological analysis.