%0 Generic %1 Sonnenfeld2011 %A Sonnenfeld, Alessandro %A Treu, Tommaso %A Gavazzi, Raphael %A Marshall, Philip J. %A Auger, Mattew W. %A Suyu, Sherry H. %A Koopmans, Leon V. E. %A Bolton, Adam S. %D 2011 %K early imf salpeter type %T Evidence for dark matter contraction and a Salpeter IMF in a massive early-type galaxy %U http://arxiv.org/abs/1111.4215 %X Stars and dark matter account for most of the mass of early-type galaxies, but uncertainties in the stellar population and the dark matter profile make it challenging to distinguish between the two components. Nevertheless, precise observations of stellar and dark matter are extremely valuable for testing the many models of structure formation and evolution. We present a measurement of the stellar mass and inner slope of the dark matter halo of a massive early-type galaxy at $z=0.222$. The galaxy is the foreground deflector of the double Einstein ring gravitational lens system SDSSJ0946+1006, also known as the "Jackpot". By combining the tools of lensing and dynamics, we first constrain the mean slope of the total mass density profile ($\rho_totr^-\gamma'$) within the radius of the outer ring to be $\gamma' = 1.98\pm0.02\pm0.01$. Then we obtain a bulge-halo decomposition, assuming a power-law form for the dark matter halo. Our analysis yields $\gamma_DM = 1.7\pm0.2$ for the inner slope of the dark matter profile, in agreement with theoretical findings on the distribution of dark matter in ellipticals, and a stellar mass from lensing and dynamics $M_*^LD = 5.5_-1.3^+0.4\times10^11M_\Sun$. By comparing this measurement with stellar masses inferred from stellar population synthesis fitting we find that a Salpeter IMF provides a good description of the stellar population of the lens while a Chabrier IMF is ruled out at the 95% confidence level. Our data suggest that growth by accretion of small systems from a compact red nugget is a plausible formation scenario for this object.

@misc{Sonnenfeld2011, abstract = { Stars and dark matter account for most of the mass of early-type galaxies, but uncertainties in the stellar population and the dark matter profile make it challenging to distinguish between the two components. Nevertheless, precise observations of stellar and dark matter are extremely valuable for testing the many models of structure formation and evolution. We present a measurement of the stellar mass and inner slope of the dark matter halo of a massive early-type galaxy at $z=0.222$. The galaxy is the foreground deflector of the double Einstein ring gravitational lens system SDSSJ0946+1006, also known as the "Jackpot". By combining the tools of lensing and dynamics, we first constrain the mean slope of the total mass density profile ($\rho_{\rm{tot}}\propto r^{-\gamma'}$) within the radius of the outer ring to be $\gamma' = 1.98\pm0.02\pm0.01$. Then we obtain a bulge-halo decomposition, assuming a power-law form for the dark matter halo. Our analysis yields $\gamma_{\rm{DM}} = 1.7\pm0.2$ for the inner slope of the dark matter profile, in agreement with theoretical findings on the distribution of dark matter in ellipticals, and a stellar mass from lensing and dynamics $M_*^{\rm{LD}} = 5.5_{-1.3}^{+0.4}\times10^{11}M_\Sun$. By comparing this measurement with stellar masses inferred from stellar population synthesis fitting we find that a Salpeter IMF provides a good description of the stellar population of the lens while a Chabrier IMF is ruled out at the 95% confidence level. Our data suggest that growth by accretion of small systems from a compact red nugget is a plausible formation scenario for this object. }, added-at = {2011-11-21T18:07:25.000+0100}, author = {Sonnenfeld, Alessandro and Treu, Tommaso and Gavazzi, Raphael and Marshall, Philip J. and Auger, Mattew W. and Suyu, Sherry H. and Koopmans, Leon V. E. and Bolton, Adam S.}, biburl = {https://www.bibsonomy.org/bibtex/27c86e1334055e4992ab70a4cb78e2637/miki}, description = {[1111.4215] Evidence for dark matter contraction and a Salpeter IMF in a massive early-type galaxy}, interhash = {e5b7a3d64418d4b39e17f08e6ac76504}, intrahash = {7c86e1334055e4992ab70a4cb78e2637}, keywords = {early imf salpeter type}, note = {cite arxiv:1111.4215 Comment: 16 pages, 15 figures, submitted to ApJ}, timestamp = {2011-11-21T18:07:25.000+0100}, title = {Evidence for dark matter contraction and a Salpeter IMF in a massive early-type galaxy}, url = {http://arxiv.org/abs/1111.4215}, year = 2011 }