Revisiting the photometric properties of early-type galaxies in the Virgo cluster

GONZÁLEZ, N.; SMITH CASTELLI, A.; FAIFER, F.; FORTE, J.C.

Buenos Aires

Workshop; Second Workshop on Numerical and Observational Astrophysics: ”From the First Structures to the Universe Today”; 2011

IAFE

The colour-magnitude relation (CMR) of early-type galaxies is a well studied photometric relation. In the colour-magnitude diagram, elliptical and lenticular galaxies define a sequence in the sense that the more massive systems are redder than the fainter ones. Spectroscopic studies of giant and dwarf ellipticals have shown that this relation would be mainly driven by metallicity and star formation effects. It is widely accepted that the CMR in groups and clusters of galaxies is linear along its extension, and that it shows no perceptible change of slope from the bright galaxies to the dwarf regime, except, perhaps, at the very bright end. In addition, there is strong evidence for the universality of this relation in clusters of galaxies. However, non-linear trends for the CMR of the Virgo cluster have been reported by Ferrarese et al. (2006, ApJS, 164, 334) and Janz & Lisker (2009, ApJ, 696, L102), in contrast to the results found in more distant associations. In this contribution, and as part of the degree thesis of Nélida González, we revisit the CMR of the Virgo cluster through the publicly available data of the "Virgo Advanced Camera Survey". We explore if the non-linearity found for this cluster may be related with a morphological misclassification of some galaxies of the sample.