The details of bulge formation via collapse , mergers , secular processes or their interplay remain unresolved .
To start answering this question and quantify the importance of distinct mechanisms , we mapped a sample of three galactic bulges using data from the integral field spectrograph WiFeS on the ANU 2.3m telescope in Siding Spring Observatory .
Its high resolution gratings ( R \sim 7000 ) allow us to present a detailed kinematic and stellar population analysis of their inner structures with classical and novel techniques .
The comparison of those techniques calls for the necessity of inversion algorithms in order to understand complex substructures and separate populations .
We use line-strength indices to derive SSP-equivalent ages and metallicities .
Additionally , we use full spectral fitting methods , here the code STECKMAP , to extract their star formation histories .
The high quality of our data allows us to study the 2D distribution of different stellar populations ( i.e .
young , intermediate , and old ) .
We can identify their dominant populations based on these age-discriminated 2D light and mass contribution .
In all galactic bulges studied , at least 50 % of the stellar mass already existed 12 Gyrs ago , more than currently predicted by simulations .
A younger component ( age between \sim 1 to \sim 8 Gyrs ) is also prominent and its present day distribution seems to be affected much more strongly by morphological structures , especially bars , than the older one .
This in-depth analysis of the three bulges supports the notion of increasing complexity in their evolution , likely to be found in numerous bulge structures if studied at this level of detail , which can not be achieved by mergers alone and require a non-negligible contribution of secular evolution .