Modelling the quenching of star formation activity from the evolution of
  the colour-magnitude relation in VIPERS
  We study the evolution of the colour-magnitude relation for galaxies in the
VIMOS Public Extragalactic Redshift Survey (VIPERS) by introducing the concept
of the bright edge, and use this to derive constraints on the quenching of star
formation activity in galaxies over the redshift range $0.5 < z < 1.1$. The
bright-edge of the colour-magnitude diagram evolves with little dependence on
galaxy colour, and therefore on the amount of star formation taking place in
bright galaxies. We modelled this evolution with delayed exponential star
formation histories (SFHs), to better understand the time-scale of the turn-off
in star formation activity. We show that using SFHs without quenching, the
transition from the blue cloud to the red sequence is too slow. This indicates
that a scenario purely driven by the consumption of the gas inside each galaxy
does not reproduce the observed evolution of the colour-magnitude bright edge.
Among the quenching scenarios explored, the one that best matches the
observations assumes that galaxies stop their star formation at a randomly
selected time with a uniform distribution up to $2.5$ Gyr. We argue that
quenching is required over a wide range of stellar masses. Qualitatively
similar evolution of the bright edge is found in the predictions of a
semi-analytical galaxy formation model, but quantitatively there are marked
differences with the observations. This illustrates the utility of the bright
edge as a test of galaxy formation models. The evolution changes and no longer
matches the observed trend if feedback from heating by active galactic nuclei
is turned off.
