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

Heymans, Catherine; Bell, Eric F.; Rix, Hans-Walter;Barden, Marco; Borch, Andrea; Caldwell, John A. R.;McIntosh, Daniel H.; Meisenheimer, Klaus;Peng, Chien Y.; Wolf, Christian;Beckwith, Steven V. W.; Häußler, Boris; Jahnke, Knud;Jogee, Shardha; Sánchez, Sebastian F.;Somerville, Rachel; Wisotzki, Lutz. A weak lensing estimate from GEMS of the virial to stellar mass ratio in massive galaxies to z ~ 0.8. Monthly Notices of the Royal Astronomical Society: Letters. 2006, Vol. Volume 371, Issue 1, pp. L60-L64., p. -2006.

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 with estimates of stellar mass Mstar. For a complete sample of galaxies with log(Mstar/Msolar) > 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 Ω*b/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.