Dynamical masses of early-type galaxies at z~2: Are they truly superdense?

Understand

We measured stellar velocity dispersions sigma and dynamical masses of 9 massive (M~10^11 Msun) early-type galaxies (ETG) from the GMASS sample at redshift 1.4<z<2.0.

• The sigma are based on individual spectra for two galaxies at z~1.4 and on a stacked spectrum for 7 galaxies with 1.6<z<2.0, with 202-h of exposure at the ESO Very Large Telescope.
• We constructed detailed axisymmetric dynamical models for the objects, based on the Jeans equations, taking the observed surface brightness (from deep HST/ACS observations), PSF and slit effects into account.
• Our dynamical masses M_Jeans agree within ~30% with virial estimates M_vir=5*Re*sigma^2/G, although the latter tend to be smaller.