Subaru Weak Lensing Measurements of Four Strong Lensing Clusters: Are Lensing Clusters Over-Concentrated?

TL;DR

This study combines strong and weak lensing data from Subaru observations to analyze four galaxy clusters, finding they are slightly more concentrated than LCDM predictions, which supports the existence of a concentration excess in lensing-selected clusters.

Contribution

It provides the first combined strong and weak lensing analysis of four clusters with detailed modeling, confirming a slight concentration excess and expanding the sample size to ten clusters.

Findings

All four clusters are more concentrated than LCDM predictions.

Combining strong and weak lensing improves mass profile constraints.

Clusters with larger Einstein radii tend to be more concentrated.

Abstract

We derive radial mass profiles of four strong lensing selected clusters which show prominent giant arcs (Abell 1703, SDSS J1446+3032, SDSS J1531+3414, and SDSS J2111-0115), by combining detailed strong lens modeling with weak lensing shear measured from deep Subaru Suprime-cam images. Weak lensing signals are detected at high significance for all four clusters, whose redshifts range from z=0.28 to 0.64. We demonstrate that adding strong lensing information with known arc redshifts significantly improves constraints on the mass density profile, compared to those obtained from weak lensing alone. While the mass profiles are well fitted by the universal form predicted in N-body simulations of the LCDM model, all four clusters appear to be slightly more centrally concentrated (the concentration parameters c_vir \sim 8) than theoretical predictions, even after accounting for the bias toward higher concentrations inherent in lensing selected samples. Our results are consistent with previous studies which similarly detected a concentration excess, and increases the total number of clusters studied with the combined strong and weak lensing technique to ten. Combining our sample with previous work, we find that clusters with larger Einstein radii are more anomalously concentrated. We also present a detailed model of the lensing cluster A1703 with constraints from multiple image families, and find the dark matter inner density profile to be cuspy with the slope consistent with -1, in agreement with expectations.