Most pseudo-bulges can be formed at later stages of major mergers
  Most giant spiral galaxies have pseudo or disk-like bulges that are
considered to be the result of purely secular processes. This may challenge the
hierarchical scenario predicting about one major merger per massive galaxy
($>$$3\times 10^{10} M_{\odot}$) since the last $\sim$ 9 billion years. Here we
verify whether or not the association between pseudo-bulges and secular
processes is irrevocable. Using GADGET2 N-body/SPH simulations, we have
conducted a systematic study of remnants of major mergers which progenitors
have been selected (1) to follow the gas richness-look back time relationship,
and (2) with a representative distribution of orbits and spins in a
cosmological frame. Analyzing the surface-mass density profile of both nearby
galaxies and merger remnants with two components, we find that most of them
show pseudo-bulges or bar dominated centers. Even if some orbits lead to
classical bulges just after the fusion, the contamination by the additional gas
that gradually accumulates to the center and forming stars later on, leads to
remnants apparently dominated by pseudo-bulges. We also found that simple SPH
simulations should be sufficient to form realistic spiral galaxies as remnants
of ancient gas-rich mergers without need for specifically tuned feedback
conditions. We then conclude that pseudo-bulges and bars in spiral galaxies are
natural consequences of major mergers when they are realized in a cosmological
context, i.e., with gas-rich progenitors as expected when selected in the
distant Universe.
