2010MNRAS.405..257M

Weak lensing work can be badly compromised by unlensed foreground and cluster members which dilute the true lensing signal. We show how the lensing amplitude in multicolour space can be harnessed to securely separate cluster members from the foreground and background populations for three massive clusters, A1703 (z = 0.258), A370 (z = 0.375) and RXJ1347-11 (z = 0.451) imaged with Subaru. The luminosity functions of these clusters when corrected for dilution show similar faint-end slopes, α ≃ - 1.0, with no marked faint-end upturn to our limit of M_R ≃ - 15.0, and only a mild radial gradient. In each case, the radial profile of the mass-to-light ratio (M/L) peaks at intermediate radius, ≃ 0.2r_vir, at a level of 300-500(M/L_R)_☉, and then falls steadily towards ∼ 100(M/L_R)_☉ at the virial radius, similar to the mean field level. This behaviour is likely due to the relative paucity of central late-type galaxies, whereas for the E/S0 sequence only a mild radial decline in M/L is found for each cluster. We discuss this behaviour in the context of detailed simulations where predictions for tidal stripping may now be tested accurately with observations.