The MAGPI Survey -- science goals, design, observing strategy, early
  results and theoretical framework
  We present an overview of the Middle Ages Galaxy Properties with Integral
Field Spectroscopy (MAGPI) survey, a Large Program on ESO/VLT. MAGPI is
designed to study the physical drivers of galaxy transformation at a lookback
time of 3-4 Gyr, during which the dynamical, morphological, and chemical
properties of galaxies are predicted to evolve significantly. The survey uses
new medium-deep adaptive optics aided MUSE observations of fields selected from
the GAMA survey, providing a wealth of publicly available ancillary
multi-wavelength data. With these data, MAGPI will map the kinematic and
chemical properties of stars and ionised gas for a sample of 60 massive (> 7 x
10^10 M_Sun) central galaxies at 0.25 < z <0.35 in a representative range of
environments (isolated, groups and clusters). The spatial resolution delivered
by MUSE with Ground Layer Adaptive Optics (GLAO, 0.6-0.8 arcsec FWHM) will
facilitate a direct comparison with Integral Field Spectroscopy surveys of the
nearby Universe, such as SAMI and MaNGA, and at higher redshifts using adaptive
optics, e.g. SINS. In addition to the primary (central) galaxy sample, MAGPI
will deliver resolved and unresolved spectra for as many as 150 satellite
galaxies at 0.25 < z <0.35, as well as hundreds of emission-line sources at z <
6. This paper outlines the science goals, survey design, and observing strategy
of MAGPI. We also present a first look at the MAGPI data, and the theoretical
framework to which MAGPI data will be compared using the current generation of
cosmological hydrodynamical simulations including EAGLE, Magneticum,
HORIZON-AGN, and Illustris-TNG. Our results show that cosmological
hydrodynamical simulations make discrepant predictions in the spatially
resolved properties of galaxies at z ~ 0.3. MAGPI observations will place new
constraints and allow for tangible improvements in galaxy formation theory.
