Chemical evolution of Local Group dwarf galaxies in a cosmological
  context -- I. A new modelling approach and its application to the Sculptor
  dwarf spheroidal galaxy
  We present a new approach for chemical evolution modelling, specifically
designed to investigate the chemical properties of dwarf galaxies in a full
cosmological framework. In particular, we focus on the Sculptor dwarf
spheroidal galaxy as a test bed for our model. We select four candidate
Sculptor-like galaxies from the satellite galaxy catalogue generated by
implementation of a version of the Munich semi-analytic model for galaxy
formation on the level 2 Aquarius dark matter simulations. We follow explicitly
the evolution of several chemical elements, both in the cold gas out of which
the stars form and in the hot medium residing in the halo. We take into account
in detail the lifetimes of stars of different initial masses, the distribution
of the delay times for type Ia supernova explosions and the dependency of the
stellar yields from the initial metallicity of the stars. We allow large
fractions of metals to be deposited into the hot phase, either directly as
stars die or through reheated gas flows powered by supernova explosions. In
order to reproduce both the observed metallicity distribution function and the
observed abundance ratios of long-lived stars of Sculptor, large fractions of
the reheated metals must never re-enter regions of active star formation. Our
analysis sets further constraints on the semi-analytical models and, at large,
on possible metal enrichment scenarios for the Sculptor dwarf spheroidal
galaxy.
