  Aims. This study aims to explore the relationship between the physical
properties of different galaxy subclasses and their environment based on the
analysis of 31 631 VIMOS Public Extragalactic Redshift Survey (VIPERS) galaxies
observed at 0.5 < z < 0.9.
  Methods. We use the results of an unsupervised clustering algorithm to
distinguish 11 subclasses of VIPERS galaxies based on the multi-dimensional
feature space defined by rest-frame UV to NIR colours presented in Siudek et al
(2018a). We investigate the relationship between the properties of these
subclasses of galaxies and their local environment, defined as the galaxy
density contrast derived from the 5th nearest neighbour technique.
  Results. We confirm that the galaxy population-density relation is already in
place at z ~ 0.9, with the blue galaxy fraction decreasing with density,
compensated by an increase of the red fraction. On average red galaxies in the
high-density environment are larger by 28% than the ones in low-density
environments. In particular, we find one group of galaxies, subclass C3, whose
increase of size with time can be explained mainly as the result of mergers;
for other red subclasses, mergers would not seem to play a major role (subclass
C2) or play a negligible role (subclass C1). The properties of the green
galaxies (subclasses C4-6) depend on whether their stellar mass is above or
below a transition mass. Low-mass green galaxies appear to have grown through
secular processes, while in high-mass green galaxies mass assembly appears to
be dominated by mergers. When it comes to blue galaxies, the trend of
decreasing fraction with denser environments seen for the group as a whole
(subclasses C7-11) is found to be driven mostly by one group of galaxies,
subclass C10. These are compact low-mass galaxies with high sSFRs, that are
preferentially found in low-density environments.
