%0 Generic %1 Spiniello2011 %A Spiniello, C. %A Koopmans, L. V. E. %A Trager, S. C. %A Czoske, O. %A Treu, T. %D 2011 %K IMF darkmatter early-type %T The X-Shooter Lens Survey - I. Dark-Matter Domination and a Salpeter-type IMF in a Massive Early-type Galaxy %U http://arxiv.org/abs/1103.4773 %X We present the first results from the X-shooter Lens Survey (XLENS): an analysis of the massive early-type galaxy SDSS J1148+1930 at redshift z=0.444. We combine its extended kinematic profile - derived from spectra obtained with X-shooter on the ESO Very Large Telescope - with strong gravitational lensing and multi-color information derived from SDSS images. Our main results are (i) The luminosity-weighted stellar velocity dispersion is <f_\ast>(<Reff) = 351 10 km/s, more accurate and considerably lower than a previously published value of \sim450km/s. (ii) A single-component (stellar plus dark) mass model of the lens galaxy yields a logarithmic total-density slope of \gamma' = 1.72+0.05 (\rho r^(-\gamma')). (iii) The projected stellar mass fraction, derived solely from lensing, is f(<Reff) = 0.19+0.04-0.09 inside the Einstein radius for a Hernquist profile and no anisotropy. The dark-matter fraction inside the effective radius f(<Reff) = 0.60+0.15\pm0.1 . (iv) Based on the SDSS colors, we find f_\ast(<Reff)=0.17 0.06 for a Salpeter IMF and f_\ast(<Reff)=0.07 0.018 for a Chabrier IMF. The lensing and dynamics constraints on the stellar mass fraction agree well with those independently derived from the SDSS colors for a Salpeter IMF, preferred over Chabrier. Dwarf-rich IMFs in the lower mass range of 0.1-0.7 solar mass, with \alpha > 3 (with dN/dM M^(-\alpha)) - recently suggested by van Dokkum & Conroy for massive ETGs - are excluded at the > 90 % C.L. and in some cases violate the total lensing-derived mass limit. We conclude that this very massive early-type galaxies is dark-matter dominated inside one effective radius, extending the trend recently found from massive SLACS galaxies, with a total density slope more shallow than isothermal. We exclude IMFs with \alpha = -3.5 at the > 90% CL, based on constraints set by lensing and dynamics.

@misc{Spiniello2011, abstract = { We present the first results from the X-shooter Lens Survey (XLENS): an analysis of the massive early-type galaxy SDSS J1148+1930 at redshift z=0.444. We combine its extended kinematic profile - derived from spectra obtained with X-shooter on the ESO Very Large Telescope - with strong gravitational lensing and multi-color information derived from SDSS images. Our main results are (i) The luminosity-weighted stellar velocity dispersion is <f_\ast>(<Reff) = 351 \pm 10 km/s, more accurate and considerably lower than a previously published value of \sim450km/s. (ii) A single-component (stellar plus dark) mass model of the lens galaxy yields a logarithmic total-density slope of {\gamma}' = 1.72+0.05 ({\rho} \propto r^(-{\gamma}')). (iii) The projected stellar mass fraction, derived solely from lensing, is f(<Reff) = 0.19+0.04-0.09 inside the Einstein radius for a Hernquist profile and no anisotropy. The dark-matter fraction inside the effective radius f(<Reff) = 0.60+0.15\pm0.1 . (iv) Based on the SDSS colors, we find f_\ast(<Reff)=0.17 \pm 0.06 for a Salpeter IMF and f_\ast(<Reff)=0.07 \pm 0.018 for a Chabrier IMF. The lensing and dynamics constraints on the stellar mass fraction agree well with those independently derived from the SDSS colors for a Salpeter IMF, preferred over Chabrier. Dwarf-rich IMFs in the lower mass range of 0.1-0.7 solar mass, with {\alpha} > 3 (with dN/dM \propto M^(-{\alpha})) - recently suggested by van Dokkum & Conroy for massive ETGs - are excluded at the > 90 % C.L. and in some cases violate the total lensing-derived mass limit. We conclude that this very massive early-type galaxies is dark-matter dominated inside one effective radius, extending the trend recently found from massive SLACS galaxies, with a total density slope more shallow than isothermal. We exclude IMFs with {\alpha} = -3.5 at the > 90% CL, based on constraints set by lensing and dynamics. }, added-at = {2011-03-25T16:14:28.000+0100}, author = {Spiniello, C. and Koopmans, L. V. E. and Trager, S. C. and Czoske, O. and Treu, T.}, biburl = {https://www.bibsonomy.org/bibtex/2f753d7fa3f20e6038b1411a91e3f1680/miki}, description = {[1103.4773] The X-Shooter Lens Survey - I. Dark-Matter Domination and a Salpeter-type IMF in a Massive Early-type Galaxy}, interhash = {93e81e5ae0158fa32f2b0e7b90200155}, intrahash = {f753d7fa3f20e6038b1411a91e3f1680}, keywords = {IMF darkmatter early-type}, note = {cite arxiv:1103.4773 }, timestamp = {2011-03-25T16:14:28.000+0100}, title = {The X-Shooter Lens Survey - I. Dark-Matter Domination and a Salpeter-type IMF in a Massive Early-type Galaxy}, url = {http://arxiv.org/abs/1103.4773}, year = 2011 }