Using angular momentum maps to detect kinematically distinct galactic
  components
  In this work we introduce a physically motivated method of performing
disc/spheroid decomposition of simulated galaxies, which we apply to the Eagle
sample. We make use of the HEALPix package to create Mollweide projections of
the angular momentum map of each galaxy's stellar particles. A number of
features arise on the angular momentum space which allows us to decompose
galaxies and classify them into different morphological types. We assign
stellar particles with angular separation of less/greater than 30 degrees from
the densest grid cell on the angular momentum sphere to the disc/spheroid
components, respectively. We analyse the spatial distribution for a subsample
of galaxies and show that the surface density profiles of the disc and spheroid
closely follow an exponential and a Sersic profile, respectively. In addition
discs rotate faster, have smaller velocity dispersions, are younger and are
more metal rich than spheroids. Thus our morphological classification
reproduces the observed properties of such systems. Finally, we demonstrate
that our method is able to identify a significant population of galaxies with
counter-rotating discs and provide a more realistic classification of such
systems compared to previous methods.
