http://arxiv.org/abs/1512.04531
One major problem of current theoretical models of galaxy formation is given by their inability to reproduce the apparently “anti-hierarchical” evolution of galaxy assembly: massive galaxies appear to be in place since $z\sim 3$, while a significant evolution is measured for lower mass galaxies, whose number densities increase significantly with decreasing redshift. In this work, we perform a systematic analysis of the influence of different stellar feedback schemes. Our analysis is carried out in the framework of GAEA, a new semi-analytic model that includes a self-consistent treatment for the timings of gas, metal and energy recycling, as well for the chemical yields. We show this to be crucial in order to use observational measurements of the metal content as independent and powerful constraints for the adopted feedback schemes. We find that the observed trends can be reproduced in the framework of either a strong ejective or preventive feedback model. In the former case, the gas ejection rate must decrease significantly with cosmic time, e.g. following parametrizations of the recent cosmological “FIRE” simulations. In the latter case, the re-incorporation time scale is also required to vary with halo mass, as found by previous work. Irrespective of the feedback scheme used, our successful models always imply that up to 60-70 per cent of the baryons reside in an “ejected” reservoir and are unavailable for cooling at high redshift. The same schemes predict physical properties of model galaxies (in terms of e.g. gas content, colour, age, and metallicity) that are in much better agreement with observational data than our previous fiducial model. Our investigation suggests that the overall fraction of passive galaxies is primarily determined by internal physical processes, with environment playing a secondary role, and being important only for the lowest mass galaxies.
M. Hirschmann, G. Lucia and F. Fontanot
Wed, 16 Dec 15
57/69
Comments: 29 pages, 19 figures, submitted to MNRAS
You must be logged in to post a comment.