Evolution of Field Spiral Galaxies up to Redshiftsz= 1

Abstract

We have gained intermediate-resolution spectroscopy with the FORS instruments of the Very Large Telescope (VLT) and high-resolution imaging with the Advanced Camera for Surveys aboard HST for a sample of 220 distant field spiral galaxies within the FORS Deep Field and William Herschel Deep Field. Spatially resolved rotation curves were extracted and fitted with synthetic velocity fields that take into account all geometric and observational effects, such as blurring due to the slit width and seeing influence. Using these fits, the maximum rotation velocity Vmax could be determined for 124 galaxies that cover the redshift range 0.1 < z < 1.0 and comprise a variety of morphologies from early-type spirals to very late types and irregulars. The luminosity-rotation velocity distribution of this sample, which represents an average look-back time of ~5 Gyr, is offset from the Tully-Fisher relation (TFR) of local low-mass spirals, whereas the distant high-mass spirals are compatible with the local TFR. Taking the magnitude-limited character of our sample into account, we show that the slope of the local and the intermediate- z TFR would be in compliance if its scatter decreased by more than a factor of 3 between z ≈ 0.5 and 0. Accepting this large evolution of the TFR scatter, we hence find no strong evidence for a mass- or luminosity-dependent evolution of disk galaxies. On the other hand, we derive stellar mass-to-luminosity ratios (M/L) that indicate a luminosity-dependent evolution in the sense that distant low-luminosity disks have much lower M/L than their local counterparts, while high-luminosity disks barely evolved in M/L over the covered redshift range. This could be the manifestation of the "downsizing" effect, i.e., the successive shift of the peak of star formation from high-mass to low-mass galaxies toward lower redshifts. This trend might be canceled out in the TF diagram due to the simultaneous evolution of multiple parameters. We also estimate the ratios between stellar and total masses, finding that these remained constant since z = 1, as would be expected in the context of hierarchically growing structure.