The VIMOS Public Extragalactic Redshift Survey (VIPERS): Downsizing of
  the blue cloud and the influence of galaxy size on mass quenching over the
  last eight billion years
  We use the full VIPERS redshift survey in combination with SDSS-DR7 to
explore the relationships between star-formation history (using d4000), stellar
mass and galaxy structure, and how these relationships have evolved since z~1.
We trace the extents and evolutions of both the blue cloud and red sequence, by
fitting double Gaussians to the d4000 distribution of galaxies in narrow
stellar mass bins, for four redshift intervals over 0<z<1. This reveals
downsizing in star formation, as the high-mass limit of the blue cloud retreats
steadily with time from M*~10^11.2 M_sun at z~0.9 to M*~10^10.7 M_sun by the
present day. The number density of massive blue-cloud galaxies (M*>10^11 M_sun,
d4000<1.55) drops sharply by a factor five between z~0.8 and z~0.5. These
galaxies are becoming quiescent at a rate that largely matches the increase in
the numbers of massive passive galaxies seen over this period. We examine the
size-mass relation of blue cloud galaxies, finding that its high-mass boundary
runs along lines of constant M*/r_e or equivalently inferred velocity
dispersion. Larger galaxies can continue to form stars to higher stellar masses
than smaller galaxies. As blue cloud galaxies approach this high-mass limit,
they start to be quenched, their d4000 values increasing to push them towards
the green valley. In parallel, their structures change, showing higher Sersic
indices and central stellar mass densities. For these galaxies, bulge growth is
necessary for them to reach the high-mass limit of the blue cloud and be
quenched by internal mechanisms. The blue cloud galaxies that are being
quenched at z~0.8 lie along the same size-mass relation as present day
quiescent galaxies, and seem the likely progenitors of today's S0s.
