The clustering of galaxies with pseudo bulge and classical bulge in the
  local Universe
  We investigate the clustering properties and close neighbour counts for
galaxies with different types of bulges and stellar masses. We select samples
of "classical" and "pseudo" bulges, as well as "bulge-less" disk galaxies,
based on the bulge/disk decomposition catalog of SDSS galaxies provided by
Simard et al. (2011). For a given galaxy sample we estimate: the projected
two-point cross-correlation function with respect to a spectroscopic reference
sample, w_p(r_p), and the average background-subtracted neighbour count within
a projected separation using a photometric reference sample, N_neighbour(<r_p).
We compare the results with the measurements of control samples matched in
color, concentration and redshift. We find that, when limited to a certain
stellar mass range and matched in color and concentration, all the samples
present similar clustering amplitudes and neighbour counts on scales above
~0.1h^{-1}Mpc. This indicates that neither the presence of a central bulge, nor
the bulge type is related to intermediate-to-large scale environments. On
smaller scales, in contrast, pseudo-bulge and pure-disk galaxies similarly show
strong excess in close neighbour count when compared to control galaxies, at
all masses probed. For classical bulges, small-scale excess is also observed
but only for M_stars < 10^{10} M_sun; at higher masses, their neighbour counts
are similar to that of control galaxies at all scales. These results imply
strong connections between galactic bulges and galaxy-galaxy interactions in
the local Universe, although it is unclear how they are physically linked in
the current theory of galaxy formation.
