Comparison of Cluster Lensing Profiles with Lambda CDM Predictions

Understand

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<c_{vir}<15 (<c_{vir}> = 10.4 \pm 0.9), compared to the relatively shallow profiles predicted by the Lambda CDM model, c_{vir}=5.1 \pm 1.1 (for <M_{vir}> =1.25\times 10^{15}M_{\odot}/h).
• This represents a 4sigma 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.