Authors: Marc Balcells, Alister W. Graham, Reynier F. Peletier
Abstract: The bulge contribution to the inner density profile of a galaxy is well traced by the bulge's NIR surface brightness profile. We have mapped the surface brightness profiles of bulges using HST/NICMOS imaging. Most bulges possess additional nuclear components of 20-200 pc scales, and frequently also unresolved nuclear star clusters (< 20 pc). These additional systems are the densest components in disk galaxies, and they are responsible for giving many bulges the reputation of having a high (stellar) concentration. However, most (Sersic R1/n) bulges typically have low concentration, 1 < n < 2.5. We cannot confirm the bi-modal distribution of bulge profiles reported by others, and suggest that the alleged bi-modality may be related to selectively excluding/including the easy/difficult to detect nuclear components in low/high-n bulges.