The impact of ISM turbulence, clustered star formation and feedback on
  galaxy mass assembly through cold flows and mergers
  Two of the dominant channels for galaxy mass assembly are cold flows (cold
gas supplied via the filaments of the cosmic web) and mergers. How these
processes combine in a cosmological setting, at both low and high redshift, to
produce the whole zoo of galaxies we observe is largely unknown. Indeed there
is still much to understand about the detailed physics of each process in
isolation. While these formation channels have been studied using
hydrodynamical simulations, here we study their impact on gas properties and
star formation (SF) with some of the first simulations that capture the
multiphase, cloudy nature of the interstellar medium (ISM), by virtue of their
high spatial resolution (and corresponding low temperature threshold). In this
regime, we examine the competition between cold flows and a
supernovae(SNe)-driven outflow in a very high-redshift galaxy (z {\approx} 9)
and study the evolution of equal-mass galaxy mergers at low and high redshift,
focusing on the induced SF. We find that SNe-driven outflows cannot reduce the
cold accretion at z {\approx} 9 and that SF is actually enhanced due to the
ensuing metal enrichment. We demonstrate how several recent observational
results on galaxy populations (e.g. enhanced HCN/CO ratios in ULIRGs, a
separate Kennicutt Schmidt (KS) sequence for starbursts and the population of
compact early type galaxies (ETGs) at high redshift) can be explained with
mechanisms captured in galaxy merger simulations, provided that the multiphase
nature of the ISM is resolved.
