Graziano COPPA
(INAF - Astronomical Observatory of Bologna / University of Bologna)
We developed two independent methods for classifying galaxies according to their intrinsic properties, and applied them to the zCOSMOS 10k galaxy sample: the first method relies on spectral properties, colours, and morphology, treated as independent and combined together to build a three dimensional “cube” of classification. The second method is an application of statistical analyses such as Principal Component Analysis and Fuzzy Clustering, showing bimodality of galaxy properties treated as a whole.
Results show very good agreement between the two methods in separating blue-starforming galaxies from red-passive ones, and the existence of a narrow “green valley” region populated by transitional galaxies.