First Light And Reionisation Epoch Simulations (FLARES) I: Environmental
  Dependence of High-Redshift Galaxy Evolution
  We introduce the First Light And Reionisation Epoch Simulations (FLARES), a
suite of zoom simulations using the EAGLE model. We resimulate a range of
overdensities during the Epoch of Reionisation (EoR) in order to build
composite distribution functions, as well as explore the environmental
dependence of galaxy formation and evolution during this critical period of
galaxy assembly. The regions are selected from a large $(3.2
\;\mathrm{cGpc})^{3}$ parent volume, based on their overdensity within a sphere
of radius $14\,h^{-1}\;\mathrm{cMpc}$. We then resimulate with full
hydrodynamics, and employ a novel weighting scheme that allows the construction
of composite distribution functions that are representative of the full parent
volume. This significantly extends the dynamic range compared to smaller volume
periodic simulations. We present an analysis of the galaxy stellar mass
function (GSMF), the star formation rate distribution function (SFRF) and the
star forming sequence (SFS) predicted by \flares, and compare to a number of
observational and model constraints. We also analyse the environmental
dependence over an unprecedented range of overdensity. Both the GSMF and the
SFRF exhibit a clear double-Schechter form, up to the highest redshifts ($z =
10$). We also find no environmental dependence of the SFS normalisation. The
increased dynamic range probed by FLARES will allow us to make predictions for
a number of large area surveys that will probe the EoR in coming years, such as
WFIRST and Euclid.
