Secular Evolution of Bulges Induced by Satellite Accretion

Abstract

Satellite accretion events have been invoked for mimicking the internal secular evolutionary processes of bulge growth (Kormendy & Kennicutt 2004). In order to investigate this question, we perform N-body models of the accretion of satellites onto disk galaxies. A scaling between the primary and the satellite based on the Tully-Fisher relation ensures that the density ratios, critical to the outcome of the accretion; are realistic. Both the bulge-to-disk ratio and the Sersic index of the remnant bulge increase as a result of the accretion. The dominant mechanism for bulge growth is the inward flow of material from the primary disk to the bulge region during the satellite decay. The models confirm that the growth of the bulge out of disk material, a central ingredient of secular evolution models, may be triggered externally through satellite accretion. This work is described in more detail in Eliche-Moral et al. (2006).