Chemodynamical analysis of bulge stars for simulated disc galaxies
  We analyse the kinematics and chemistry of the bulge stars of two simulated
disc galaxies using our chemodynamical galaxy evolution code GCD+. First we
compare stars that are born inside the galaxy with those that are born outside
the galaxy and are accreted into the centre of the galaxy. Stars that originate
outside of the bulge are accreted into it early in its formation within 3 Gyrs
so that these stars have high [alpha/Fe] as well as having a high total energy
reflecting their accretion to the centre of the galaxy. Therefore, higher total
energy is a good indicator for finding accreted stars. The bulges of the
simulated galaxies formed through multiple mergers separated by about a Gyr.
Since [alpha/Fe] is sensitive to the first few Gyrs of star formation history,
stars that formed during mergers at different epochs show different [alpha/Fe].
We show that the [Mg/Fe] against star formation time relation can be very
useful to identify a multiple merger bulge formation scenario, provided there
is sufficiently good age information available. Our simulations also show that
stars formed during one of the merger events retain a systematically prograde
rotation at the final time. This demonstrates that the orbit of the ancient
merger that helped to form the bulge could still remain in the kinematics of
bulge stars.
