ZOMG II: Does the halo assembly history influence central galaxies and
  gas accretion?
  The growth-rate and the internal dynamics of galaxy-sized dark-matter haloes
depend on their location within the cosmic web. Haloes that sit at the nodes
grow in mass till the present time and are dominated by radial orbits.
Conversely, haloes embedded in prominent filaments do not change much in size
and are dominated by tangential orbits. Using zoom hydrodynamical simulations
including star formation and feedback, we study how gas accretes onto these
different classes of objects that, for simplicity, we dub 'accreting' and
'stalled' haloes. We find that all haloes get a fresh supply of newly accreted
gas in their inner regions, although this slowly decreases with time, in
particular for the stalled haloes. The inflow of new gas is always higher than
(but comparable with) that of recycled material. Overall, the cold-gas fraction
increases (decreases) with time for the accreting (stalled) haloes. In all
cases, a stellar disc and a bulge form at the centre of the simulated haloes.
The total stellar mass is in excellent agreement with expectations based on the
abundance-matching technique. Many properties of the central galaxies do not
seem to correlate with the large-scale environment in which the haloes reside.
However, there are two notable exceptions that characterise stalled haloes with
respect to their accreting counterparts: i) the galaxy disc contains much older
stellar populations; ii) its vertical scale-height is larger by a factor of two
or more. This thickening is likely due to the heating of the long-lived discs
by mergers and close flybys.
