2002A&A...386...12D

We estimate the total mass distribution of the galaxy cluster CL 0024+1654 from the measured source depletion due to lens magnification in the R band. Within a radius of 0.54h^–1.Mpc, a total projected mass of (8.1±3.2)x10¹⁴h^–1.M_☉ (EdS) is measured. The 1σ error here includes shot noise, source clustering, uncertainty in background count normalisation and contamination from cluster and foreground galaxies. This corresponds to a mass-to-light ratio of M/L_B=470±180. We compute the luminosity function of CL 0024+1654 in order to estimate contamination of the background source counts from cluster galaxies. Three different magnification-based reconstruction methods are employed: 1) an estimator method using a local calculation of lens shear; 2) a non-local, self-consistent method applicable to axi-symmetric mass distributions; 3) a non-local, self-consistent method for derivation of 2D mass maps. We have modified the standard single power-law slope number count theory to incorporate a break and applied this to our observations. Fitting analytical magnification profiles of different cluster models to the observed number counts, we find that CL 0024+1654 is best described either by a NFW model with scale radius r_s=334±191h^–1kpc and normalisation κ_s=0.23±0.08 or a power-law profile with slope ξ=0.61±0.11, central surface mass density κ₀=1.52±0.20 and assuming a core radius of r_core=35h^–1kpc. The NFW model predicts that the cumulative projected mass contained within a radius R scales as M(<R)=2.9x10¹⁴(R/1')^1.3-0.5lg (R/1')^h-1^M_☉. Finally, we have exploited the fact that flux magnification effectively enables us to probe deeper than the physical limiting magnitude of our observations in searching for a change of slope in the U band number counts. We rule out both a total flattening of the counts with a break up to U_AB≤26.6 and a change of slope, reported by some studies, from d logN/dm=0.4->0.15 up to U_AB≤26.4 with 95% confidence.