Stellar and Total Mass in Early-Type Lensing Galaxies

Abstract

For 18 well-observed gravitationally lensed QSOs, we compare new non-parametric mass profiles for the lensing galaxies with stellar-population models derived from published HST photometry. The large volume of parameter space searched -- with respect to the possible star formation histories -- allows us to infer robust estimates and uncertainties for the stellar masses. The most interesting results are: (1) the transition from little or no dark matter in the inner regions (