The Central kpc of Galaxy Bulges

Abstract

We study the innermost regions of bulges with surface brightness data derived from combined HST/NICMOS and ground-based NIR profiles. Bulge profiles to 1-2 kpc may be fit with Sersic laws, and show a trend with bulge-to-disk ratio: low-B/D bulges are roughly exponential, whereas higher-B/D bulges show increasing Sersic shape index $n$, indicating higher peak central densities and more extended brightness tails. N-body models of accretion of satellites onto disk-bulge-halo galaxies show that satellite accretion contributes to the increase of the shape index $n$ as the bulge grows by accretion. The N-body results demonstrate that exponential profiles are fragile to merging, hence bulges with exponential surface brightness profiles cannot have experienced significant growth by accretion of dense satellites.