Dark Energy Survey Year 1 Results: Calibration of Cluster Mis-centering in the redMaPPer Catalogs

Understand

The center determination of a galaxy cluster from an optical cluster finding algorithm can be offset from theoretical prescriptions or $N$-body definitions of its host halo center.

• These offsets impact the recovered cluster statistics, affecting both richness measurements and the weak lensing shear profile around the clusters.
• This paper models the centering performance of the \RM~cluster finding algorithm using archival X-ray observations of \RM-selected clusters.
• Assuming the X-ray emission peaks as the fiducial halo centers, and through analyzing their offsets to the \RM~centers, we find that $\sim 75\pm 8 \%$ of the \RM~clusters are well centered and the mis-centered offset follows a Gamma distribution in normalized, projected distance.