Comparison of Cluster Lensing Profiles with Λcdm Predictions1

We derive lens distortion and magnification profiles of four well known clusters observed with Subaru. Each cluster is very well fitted by the general form predicted for Cold Dark Matter (CDM) dominated halos, with good consistency found between the independent distortion and magnification measurements. The inferred level of mass concentration is surprisingly high, 8 < cvir < 15 (〈cvir〉 = 10.39± 0.91), compared to the relatively shallow profiles predicted by the ΛCDM model, cvir = 5.06±1.10 (for 〈Mvir〉 = 1.25×10M⊙/h). This represents a 4σ discrepancy, and includes the relatively modest effects of projection bias and profile evolution derived from N-body simulations, which oppose each other with little residual effect. In the context of CDM based cosmologies, this discrepancy implies clusters collapse earlier (z ≥ 1) than predicted (z < 0.5), when the Universe was correspondingly denser. Subject headings: cosmology: observations – gravitational lensing – large-scale structure of universe – galaxies: clusters: individual (A1689, A1703, A370, RXJ1347-11)