The recycling of gas and metals in galaxy formation: predictions of a dynamical feedback model
Abstract
We present results of a new feedback scheme implemented in the Munich galaxy formation model. The new scheme includes a dynamical treatment of galactic winds powered by supernovae explosions and stellar winds and is an excellent alternative to empirically-motivated recipes for feedback in galaxy formation. Model results are in good agreement with the observed luminosity function and stellar mass function for galaxies in the local Universe. In particular, the new scheme predicts a number density of dwarfs that is lower than in previous models. The model is also able to reproduce the observed mass--stellar metallicity and luminosity-gas metallicity relations. This demonstrates that our scheme provides a significant improvement in the treatment of the feedback in dwarf galaxies. A new feature of the model allows an estimate of the amount of mass and metals that haloes can permanently deposit into the IGM. It is this loss of material that leads to a suppression of star formation in small haloes and therefore to a decrease in the number density of dwarf galaxies. Despite its successes, our model does not reproduce the observed bimodality in galaxy colours. Finally, we investigate the efficiency of mass and metal injections in winds and in the intergalactic medium. We find that galaxies that reside in haloes with M_vir < 10^12.5 M_sun may deposit most of their metal mass into the intergalactic medium, while groups and clusters at z=0 have lost at most a few percent of their metals before the bulk of the halo mass was accreted.Keywords
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