The physics of galaxies 7 gyr ago
Over the past decade, redshift
surveys and multi-wavelength imaging campaigns have drawn up an
empirical picture of how many stars had formed in which types of
galaxies over the history of the universe.  However, we have yet to
unravel the individual pathways along which galaxies evolve, and the
physical processes that drive them.  Continuing with the previous
approach -- larger and deeper photometric samples -- is not adequate
to achieve this goal.  A change of focus is required.

In this ERC project I will embark on a new way to address the question
of galaxy evolution.  I will do so as Principle Investigator of the
recently approved LEGA-C observing program that has been allocated 128
nights of observation time over the next 4 years with ESO's flagship
facility the Very Large Telescope.  This new survey will produce for
2500 distant (at z~1) galaxies with, for the first time,
sufficient resolution and S/N to measure ages and chemical
compositions of their stellar populations as well as internal velocity
dispersions and dynamical masses.  This will provide an entirely new
physical description of the galaxy population 7 Gyr ago, with which I
will finally be able solve long-standing questions in galaxy formation
that were out of reach before: what is the star-formation history of
individual galaxies, why and how is star-formation ``quenched'' in
many galaxies, and to what extent do galaxies grow subsequently
through merging afterward?

LEGA-C is worldwide the largest spectroscopic survey of distant
galaxies to date, and ERC funding will be absolutely critical in
harvesting this unparallelled database.  I am seeking to extend my
research group to realize the scientific potential of this substantial
investment (6.5M Eur) of observational resources by the European
astronomy community.  Timing of the execution of the VLT program is
perfectly matched with the timeline of this ERC program.