The orbital velocity anisotropy of cluster galaxies: evolution
  In nearby clusters early-type galaxies follow isotropic orbits, while the
orbits of late-type galaxies are characterized by slightly radial anisotropy.
Little is known about the orbits of the different populations of cluster
galaxies at redshift above z~0.3. Here we investigate the redshift evolution of
the orbits of cluster galaxies using two samples of galaxy clusters spanning
similar (evolutionary corrected) mass ranges at different redshifts. The
low-redshift (z~0.0-0.1) sample is extracted from the ENACS catalog and the
high-redshift (z~0.4-0.8) sample is mostly made of clusters from the EDisCS.
For each of these samples, we solve the Jeans equation for hydrostatic
equilibrium separately for two cluster galaxy populations, characterized by the
presence and, respectively, absence of emission-lines in their spectra ('ELGs'
and 'nELGs' hereafter). Using two tracers of the gravitational potential allows
to partially break the well known mass-velocity anisotropy degeneracy.
  We find no significant evolution for the orbits of ELGs. On the other hand
the orbits of nELGs do evolve, from radial to isotropic with time. We speculate
that this evolution may be driven by the secular mass growth of galaxy clusters
during their fast accretion phase. The mass density profiles of the clusters
are well fit by NFW models both in the low-z and in the high-z samples. The
best-fit NFW concentrations and their redshift evolution are in agreement with
the predictions of Lambda CDM cosmological simulations. The evolution of the
number density profile of nELGs is opposite to that of the mass density
profile, becoming less concentrated with time, probably a result of the
transformation of ELGs into nELGs [abridged].
