3D spectroscopy with VLT/GIRAFFE IV. Angular momentum and dynamical support of intermediate redshift galaxies

Context. One of the most outstanding problems related to numerical models of galaxy formation is the so-called "angular momentum catastrophe", i.e., the inability to theoretically explain the high angular momentum observed in local disk galaxies. Aims. We study the evolution of the angular momentum from z similar to 0.6 to z = 0 to better understand the mechanisms responsible for the large angular momenta of disk galaxies observed today. This study is based on a complete sample of 32, 0.4 <= z <= 0.75 galaxies observed with FLAMES/GIRAFFE at the VLT. Their kinematics had been classified as rotating disks ( 11 galaxies), perturbed rotators (7 galaxies), or complex kinematics (14 galaxies). Methods. We have computed the specific angular momentum of disks (j(disk)) and the dynamical support of rotating disks through the V/sigma ratio. To study how angular momentum can be acquired dynamically, we compared the properties of distant and local galaxies, as a function of their kinematical class. Results. We find that distant rotating disks have essentially the same properties (j(disk) and R-d) as local disks, while distant galaxies with more complex kinematics have a significantly higher scatter in the j(disk)-V-max and R-d-V-max planes. On average, distant galaxies show lower values of V/sigma than local galaxies, the lowest V/sigma values being reached by distant galaxies showing perturbed rotation. This can probably be attributed to heating mechanisms at work in distant disks. Conclusions. We found observational evidence for a non-linear random-walk evolution of the angular momentum in galaxies during the past 8 Gyr. The evolution related to galaxies with complex kinematics can be attributed to mergers, but not to ( smooth) gas accretion alone. If galaxies observed at intermediate redshift are related to present-day spirals, then our results match the "spiral rebuilding" scenario proposed by Hammer et al. (2005) quite closely.