Bibcode
Seidel, M. K.; Cacho, R.; Ruiz-Lara, T.; Falcón-Barroso, J.; Pérez, I.; Sánchez-Blázquez, P.; Vogt, F. P. A.; Ness, M.; Freeman, K.; Aniyan, S.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 446, Issue 3, p.2837-2860
Fecha de publicación:
1
2015
Número de citas
29
Número de citas referidas
29
Descripción
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's 2.3-m telescope in Siding Spring Observatory. Its
high-resolution gratings (R ˜ 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 single stellar population 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 per cent of
the stellar mass already existed 12 Gyr ago, more than currently
predicted by simulations. A younger component (age between ˜1 and
˜8 Gyr) 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 cannot be achieved by mergers alone and require a
non-negligible contribution of secular evolution.
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