What Shapes the Luminosity Function of Galaxies?

We investigate the physical mechanisms that shape the luminosity function of galaxies in hierarchical clustering models. Beginning with the mass function of dark matter halos in the $\\Lambda$CDM cosmology, we show, in incremental steps, how gas cooling, photoionization at high redshift, feedback processes, galaxy merging and thermal conduction affect the shape of the luminosity function. We consider three processes whereby supernovae and stellar wind energy can affect the forming galaxy: (1) the reheating of cold disk gas to the halo temperature; (2) expansion of the hot, diffuse halo gas; (3) complete expulsion of cold disk gas from the halo. We demonstrate that while feedback of form (1) is able to flatten…

• LT
  Leverhulme Trust
• DU
  Durham University