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A weak lensing estimate from GEMS of the virial to stellar mass ratio in massive galaxies to z~0.8

Catherine Heymans, Eric F. Bell, Hans-Walter Rix, Marco Barden, Andrea Borch, John A. R. Caldwell, Daniel H. McIntosh, Klaus Meisenheimer, Chien Y. Peng, Christian Wolf, Steven V. W. Beckwith, Boris Haeussler, Knud Jahnke, Shardha Jogee, Sebastian F. Sanchez, Rachel Somerville, Lutz Wisotzki

astro-pharXiv:astro-ph/0606418

Abstract

We present constraints on the evolution of the virial to stellar mass ratio of galaxies with high stellar masses in the redshift range 0.2<z<0.8, by comparing weak lensing measurements of virial mass Mvir to estimates of stellar mass Mstar from COMBO-17. For a complete sample of galaxies with log(Mstar/ M) > 10.5, where the majority show an early-type morphology, we find that the virial mass to stellar mass ratio is given by Mvir/Mstar = 53+13-16. Assuming a baryon fraction from the concordance cosmology, this corresponds to a stellar fraction of baryons in massive galaxies of Omegab*/Ωb = 0.10 +/- 0.03. Analysing the galaxy sample in different redshift slices, we find little or no evolution in the virial to stellar mass ratio, and place an upper limit of ~2.5 on the growth of massive galaxies through the conversion of gas into stars from z=0.8 to the present day.

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