We aim to determine if the galactic bulge formed via mergers,  as predicted by CDM theory, or from disk instabilities, as suggested by its boxy shape, or both.

The two theories make very different predictions for the stellar kinematics of the bulge. Instability bulges are characterised by cylindrical rotation, with the bulge rotating as rapidly at high latitudes as in the plane, whereas merger bulges have a more spheroidal rotation profile with slow rotation at high latitudes.

Our AAOmega survey is measuring the stellar velocities and chemical abundances of about 28 000 stars,  which will provide a quantitative test of which kind of bulge we have in our galaxy.

The sample size is sufficient to detect a 5% merger-generated bulge underlying an instability bulge. The survey extends out of the bulge into the surrounding thin and thick disk in order to investigate the kinematical and chemical relationship between the bulge and the adjacent disk from which it may have formed. Measurements of the [Fe/H] and [alpha/Fe] distributions in the bulge and in the disk will be made as markers of chemical evolution.

The selection criteria for our stellar sample were chosen to include also the metal-poor pre-galactic first stars which are expected now to be concentrated to the bulge region.