The EAGLE simulations of galaxy formation: public release of halo and
  galaxy catalogues
  We present the public data release of halo and galaxy catalogues extracted
from the EAGLE suite of cosmological hydrodynamical simulations of galaxy
formation. These simulations were performed with an enhanced version of the
GADGET code that includes a modified hydrodynamics solver, time-step limiter
and subgrid treatments of baryonic physics, such as stellar mass loss,
element-by-element radiative cooling, star formation and feedback from star
formation and black hole accretion. The simulation suite includes runs
performed in volumes ranging from 25 to 100 comoving megaparsecs per side, with
numerical resolution chosen to marginally resolve the Jeans mass of the gas at
the star formation threshold. The free parameters of the subgrid models for
feedback are calibrated to the redshift z=0 galaxy stellar mass function,
galaxy sizes and black hole mass - stellar mass relation. The simulations have
been shown to match a wide range of observations for present-day and
higher-redshift galaxies. The raw particle data have been used to link galaxies
across redshifts by creating merger trees. The indexing of the tree produces a
simple way to connect a galaxy at one redshift to its progenitors at higher
redshift and to identify its descendants at lower redshift. In this paper we
present a relational database which we are making available for general use. A
large number of properties of haloes and galaxies and their merger trees are
stored in the database, including stellar masses, star formation rates,
metallicities, photometric measurements and mock gri images. Complex queries
can be created to explore the evolution of more than 10^5 galaxies, examples of
which are provided in appendix. (abridged)
