Fakultäten » Mathematisch-naturwissenschaftliche Fakultät » Physik-Institut » Prof. Dr. Philippe Jetzer » Tortora

Completed research project

Title / Titel Gradients in real galaxies
PDF Abstract (PDF, 14 KB)
Summary / Zusammenfassung We have analyzed the colour gradients (CGs) of » 50 000 nearby Sloan Digital Sky Survey
(SDSS) galaxies. From synthetic spectral models we derived the mean spectral properties,
and explained the observed radial trends of the colour as gradients of the stellarpopulation age and metallicity. Distinct behaviours are found for early- and late-type
galaxies (ETGs and LTGs), pointing to slightly different physical processes at work in
different morphological types and at different mass scales. In particular, the most massive
ETGs have shallow (even flat) CGs in correspondence of shallow
(negative) metallicity gradients. Similar trends of CGs with the effective
radius and the velocity dispersion are found. On the other side, LTGs have gradients
which systematically decrease with mass (and are always more negative than in ETGs).
Metallicity is found to be the main driver of the trend of colour gradients, especially for
LTGs, but age gradients are not negligible and seem to play a significant role too. We
have also been able to highlight that older galaxies have systematically shallower age and
metallicity gradients than younger ones. The emerging picture is qualitatively consistent
with the predictions from hydrodynamical and chemo-dynamical simulations: in fact,
our results for high-mass galaxies are in perfect agreement with predictions based on the
merging scenario, while the evolution of LTGs and younger and less massive ETGs seems
to be mainly driven by infall and supernovae feedback.
Publications / Publikationen Mon. Not. R. Astron. Soc., Volume 407, (2010), pp. 627
Project leadership and contacts /
Projektleitung und Kontakte
Dr. Crescenzo Tortora (Project Leader)
Prof. Philippe Jetzer
Funding source(s) /
Unterstützt durch
SNF (Personen- und Projektförderung)
Duration of Project / Projektdauer Jul 2010 to Jun 2012