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(Shortened) The combination of lensing and stellar dynamics breaks the mass-anisotropy degeneracy and provides stringent constraints on the mass distribution in early-type (E/S0) galaxies out to z~1. We present the combined results from the five field E/S0 lens galaxies at z=0. 5-1. 0 analyzed as part of the LSD Survey. We find: (i) Constant M/L models are ruled out at >99% CL for all five E/S0s. The projected dark-matter mass fractions inside the Einstein (effective) radius is fDM=0. 37-0. 72 (0. 15-0. 65) for isotropic models. (ii) The average power-law slope of the total mass distribution is =1. 75+-0. 10 for isotropic models with 0. 20 rms scatter. The ratio between the observed central stellar velocity dispersion and that from the best-fit SIE lens model is ==0. 87+-0. 04 with 0. 08 rms. Considering that '>2 and fSIE>1 have been reported for other systems, we conclude that there is a significant intrinsic scatter in the density slopes of E/S0s (rms \~15%). Hence, the isothermal approximation is not sufficiently accurate for applications that depend critically on the slope of the mass density profile (i. e. measuring H₀). (iii) The inner power-law slope of the dark-matter halo is constrained to be =1. 3 (+0. 2/-0. 4) (68% CL) for the isotropic model or an upper limit of <0. 6, if the galaxies are radially anisotropic (rᵢ=Rₑ). This is consistent with numerical simulations only for an isotropic velocity ellipsoid and if baryonic collapse and star-formation do not steepen dark-matter density profiles. (iv) The average stellar M/L evolves as d (M_*/LB) /dz =-0. 72+-0. 10, obtained via the FP. Based on lensing and dynamics we find d (M_*/LB) /dz=-0. 75+-0. 17, indicating that the M/L ratio evolution for our sample of field E/S0s is faster than those in clusters.
Treu et al. (Fri,) studied this question.