MG14 - Talk detail

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Abstract

We combine strong lensing analysis of cluster cores with velocity dispersion measurements of cluster members to separate the lensing contribution of the galaxy component from that of the smooth dark matter component and thus investigate the extend of galaxy halos in clusters. While lensing usually constrains the overall, projected mass density, the innovative use of velocity dispersion measurements as a proxy for masses of individual cluster members breaks inherent degeneracies and allows us to refine the constraints on the galaxy mass-to-light scaling relation and as a result, refine the constraints on the DM-only map. We performed such analysis in the galaxy cluster Abell 383 and found that the knowledge of cluster member velocity dispersions improves the fit by 17% in terms of the multiple images reproduction chi^2. The constraints on the smooth DM halo are improved by ~10%, while for a fiducial reference galaxy used to scale the member galaxy masses they are refined correspondingly by 50%. In addition, by performing a detailed surface brightness reconstruction of the southern giant arc, we improve by more then ~30% the constraints on the truncation radii of two close by cluster members which have measured velocity dispersions. We are now performing the same analysis on Abell 611 and Abell 1689, and plan to apply it to other clusters for which velocity dispersions measurements are available.

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