The Shape of the Luminosity Profiles of Bulges

Abstract

We extract the bulge light profiles of a sample of early type spirals, using K -band photometry and a new 2-dimensional decomposition method that does not assume a priori any surface brightness laws. We find that the shape of the light profile shows a good correlation with the morphological type of the galaxy, in the sense that the profiles tend to fall off more steeply at large radii for the later types. This trend shows that the formation of or interaction with the disk has probably affected the density distribution of the bulge. The fact that the transition in shape is continuous might also imply that most of the bulges of late type spirals were not formed by different mechanisms than the ones of early types.