Scaling Relations of Field Spirals

In the last few years, galaxies at redshifts up to z ∼ 1 have become accessible for medium–resolved spectroscopy thanks to the new generation of 10m-class telescopes. With kinematic and photometric information on spiral galaxies in this regime, well–known scaling relations like the Tully–Fisher relation (TFR) can be studied over half a Hubble time. By comparison to local samples, these studies facilitate simultaneous tests of the hierarchical merging scenario and stellar population models. Using the Very Large Telescope, we obtained spatially resolved rotation curves of 78 spiral galaxies in the FORS Deep Field (FDF), covering all Hubble types from Sa to Sm/Irr at redshifts 0.1 < z < 1.0. We find evidence for a B-band luminosity increase of up to 2 mag for low–mass spirals, whereas the most massive galaxies are of the same luminosity as their local counterparts. In effect, the TFR slope decreases significantly. This would explain the discrepant results of previous observational studies. We also present the velocity–size relation and compare it to the predictions of numerical simulations based on the hierarchical merging scenario. The scaling relations between the basic parameters of spiral galaxies — luminosity L, maximum rotation velocity V max and scalelength r d — are correlated via a two–dimensional plane which is similiar to the well-known Fundamental Plane for ellipticals (e.g., Koda, Sofue and Wada, 2000). Most famous among the projections of this plane is the Tully– Fisher relation (TFR) between V max and L (Tully and Fisher, 1977). A study of such scaling relations over different cosmic epochs offers powerful tests of different aspects of the hierarchical merging scenario and stellar population models. Nevertheless, spectroscopy of galaxies at redshifts up to z = 1 with sufficient (spectral and spatial) resolution and S/N for gaining robust information on their kinematics is a great observational challenge and * Based on observations with the ESO Very Large Telescope, run IDs 65.O-0049, 66.A-0547 and 68.A-0013.