Observing the stellar halo of Andromeda in cosmological simulations: the
  Auriga2PAndAS pipeline
  We present a direct comparison of the Pan-Andromeda Archaeological Survey
(PAndAS) observations of the stellar halo of M31 with the stellar halos of 6
galaxies from the Auriga simulations. We process the simulated halos through
the Auriga2PAndAS pipeline and create PAndAS-like mocks that fold in all
observational limitations of the survey data (foreground contamination from the
Milky Way stars, incompleteness of the stellar catalogues, photometric
uncertainties, etc). This allows us to study the survey data and the mocks in
the same way and generate directly comparable density maps and radial density
profiles. We show that the simulations are overall compatible with the
observations. Nevertheless, some systematic differences exist, such as a
preponderance for metal-rich stars in the mocks. While these differences could
suggest that M31 had a different accretion history or has a different mass
compared to the simulated systems, it is more likely a consequence of an
under-quenching of the star formation history of galaxies, related to the
resolution of the Auriga simulations. The direct comparison enabled by our
approach offers avenues to improve our understanding of galaxy formation as
they can help pinpoint the observable differences between observations and
simulations. Ideally, this approach will be further developed through an
application to other stellar halo simulations. To facilitate this step, we
release the pipeline to generate the mocks, along with the six mocks presented
and used in this contribution.
