EARLY is aimed to support a comprehensive survey of the early phases of galaxy evolution to better
understand how galaxies formed and evolved in the cosmic web of large scale structures. The goal is to
focus on the redshift range 2.5<z<7, based on a new ultra-deep spectroscopic survey on-going with
VIMOS at ESO, one of the largest ‘Large Program’ on the VLT with 648 hours allocated, conducted
by an international collaboration under the leadership of Olivier Le Fèvre.
In a ground-breaking effort, this Legacy survey will assemble more than 10,000
galaxies with VLT-VIMOS, over 1deg² in 3 fields (COSMOS, ECDFS, VVDS-02), to study the
formation and evolution of galaxies at this key epoch. This new survey will increase by one order of
magnitude the total number of spectral measurements obtained in this redshift range, including >300 new
galaxies with z>5, considerably increasing our knowledge of the galaxy population at these epochs.

This large sample of galaxies will enable a number of detailed studies from 3×109 to 5×108 years
after the BigBang, most importantly : (i) the evolution of the global star formation rate and the build-up of the
mass for different galaxy populations, (ii) the study of very young galaxies and search for the long sought
PopIII stellar populations, (iii) the evolution of the morphology of galaxies as they are building up, (iv)
the clustering of galaxies to infer the mass growth of underlying dark matter halos, (v) the contribution of
mergers to the mass growth of galaxies at these early epochs. These measurements will be used to build a
comprehensive picture describing the physical processes which regulate star formation and mass
assembly in galaxies in their early phases of evolution.
The support from the ERC will be used to conduct efficient exploitation of this leading survey. The
survey observations and data processing will be performed with new generation methods. The data will
be secured and accessed via an open database. Dedicated analysis tools will be developed to firmly
establish the properties of galaxies at these epochs. This will lead to the elaboration of a comprehensive
scenario for early galaxy evolution.