The environmental density and the bulge-to-disk ratio of disk galaxies in the local supercluster

Abstract

Relying on several samples of disk galaxies for which a detailed photometric bulge/disk decomposition has been given in the literature, we have investigated on the relation between the bulge-to-disk light ratio (B/D) and the environmental density. For nearby (z<0.01) galaxies, we provide a well-defined three-dimensional characterization of the local galaxy density. We find that the observed relation between B/D and environmental density simply reflects the average decline of B/D (and bulge luminosity) towards later morphological types coupled with the morphology-density relation. Whenever the latter effect is removed, no primary B/D-density relation is detected. Moreover, unlike previous claims, B/D appears to be unrelated to the galaxy absolute magnitude.