The hierarchical build-up of the Tully-Fisher relation (original) (raw)

2011, Monthly Notices of the Royal Astronomical Society

We use the semi-analytic model GalICS to predict the Tully-Fisher relation in the B, I and for the first time, in the K band, and its evolution with redshift, up to z ∼ 1. We refined the determination of the disk galaxies rotation velocity, with a dynamical recipe for the rotation curve, rather than a simple conversion from the total mass to maximum velocity. The new recipe takes into account the disk shape factor, and the angular momentum transfer occurring during secular evolution leading to the formation of bulges. This produces model rotation velocities that are lower by ∼ 40−50 km/s in case of Milky Way-like objects, up to ∼ 50−60 km/s at the high-mass end, and 20−30 km/s for the majority of the spirals, amounting to an average effect of ∼ 20 − 25%. We implemented stellar population models with a complete treatment of the thermally pulsing asymptotic giant branch, which leads to a revision of the mass-to-light ratio in the near-IR. Due to this effect, K band luminosities increase by ∼ 0.5 mags at redshift z = 0 and by ∼ 1 mags at z = 3, while in the I band at the same redshifts the increase amounts to ∼ 0.3 and ∼ 0.5 mags. With these two new recipes in place, the comparison between the predicted Tully-Fisher relation with a series of datasets in the optical and near-infrared, at redshifts between 0 and 1, is used as a diagnostics of the assembly and evolution of spiral galaxies in the model. The new model shows a net improvement in comparison with its original version of 2003. However, the redshift z = 0 predicted Tully-Fisher is too bright in all bands, although the model is able to reproduce the morphological differentiation observed in the K band. At redshifts z 0.4 the match between the model and data improves dramatically. We argue that this behavior is caused by inadequate star formation histories in the model galaxies at low redshifts. The star-formation rate declines too slowly, due to continuous gas infall that is not efficiently suppressed.