Disk galaxy evolution up to redshift z=1 ∗

We have performed intermediate-resolution VLT/FORS spectroscopy and HST/ACS imaging of 129 field spiral galaxies within the FORS Deep Field. The gala xies cover the redshift range 0.1 ≤ z ≤ 1.0 and comprise all types from Sa to Sdm/Im. Spatially resolved rotation curves were extracted and fitted with synthetic velocity fields that take into account all geometric (e.g., inclination and misalignment) and observational effects (in particular, blurring due to optical beam smearing and seeing). Using these fits, the maximum rotation velocity Vmax could be determined for 73 objects. The Tully-Fisher relation of this sample at a mean look-back time of ∼ 5 Gyr shows a luminosity evolution which amounts to ∼ 2 mag in rest-frame B for low-mass spirals (Vmax ≈ 100 km/s) but is negligible for high-mass spirals (Vmax ≈ 300 km/s). This confirms our previous analysis which was limited to ground-based imaging. The observed overluminosity of low-mass galaxies is at variance with predictions from simulations. On the other hand, at given Vmax, we find slightly smaller disk sizes towards higher redshifts, in compliance with the CDM hierarchical model. The observed mass-dependent luminosity evolution might therefore point towards the need for a more realistic modelling of the stellar (i.e. baryonic) compone nt in N-body codes.