The metallicity and elemental abundance maps of kinematically atypical
  galaxies for constraining minor merger and accretion histories
  Explaining the internal distribution and motions of stars and gas in galaxies
is a key aspect in understanding their evolution. In previous work we
identified five well resolved galaxies with atypical kinematics from a
cosmological simulation; two had kinematically distinct cores (KDCs), and three
had counter-rotating gas and stars (CRGD). In this paper, we show that i) the
KDC galaxies have flattening of stellar [O/Fe] at large galacto-centric radii
due to the minor mergers that gave rise to the KDCs, and ii) the CRGD galaxies
have an abrupt transition in the gas metallicity maps, from high metallicity in
the centre to very low metallicity further out. These galaxies are embedded in
dark matter filaments where there is a ready supply of near-pristine gas to
cause this effect. The non-linear increase in gas metallicity is also seen in
the radial profiles, but when the metallicity gradients are measured, the
difference is buried in the scatter of the relation. We also find that all five
galaxies are fairly compact, with small effective radii given their stellar
masses. This is because they have not experienced major mergers that
kinematically heat the stars, and would have destroyed their unusual
kinematics. In order to detect these signatures of minor mergers or accretion,
the galaxy scaling relations or radial metallicity profiles are not enough, and
it is necessary to obtain the 2D maps with integral field spectroscopy
observations.
