Comparison of Cluster Lensing Profiles with ΛCDM Predictions

Abstract

We derive lens distortion and magnification profiles of four well known\nclusters observed with Subaru. Each cluster is very well fitted by the general\nform predicted for Cold Dark Matter (CDM) dominated halos, with good\nconsistency found between the independent distortion and magnification\nmeasurements. The inferred level of mass concentration is surprisingly high,\n8<c_{vir}<15 (<c_{vir}> = 10.4 \\pm 0.9), compared to the relatively shallow\nprofiles predicted by the Lambda CDM model, c_{vir}=5.1 \\pm 1.1 (for <M_{vir}>\n=1.25\\times 10^{15}M_{\\odot}/h). This represents a 4sigma discrepancy, and\nincludes the relatively modest effects of projection bias and profile evolution\nderived from N-body simulations, which oppose each other with little residual\neffect. In the context of CDM based cosmologies, this discrepancy implies\nclusters collapse earlier (z\\geq 1) than predicted (z<0.5), when the Universe\nwas correspondingly denser.\n