Central "massive compact object" mass vs. host galaxy Sérsic index n. Filled circles represent SMBHs in elliptical galaxies, while open circles represent SMBHs in disk galaxies. The stars represent nuclear star clusters in elliptical galaxies presented in Graham & Guzmán (2003) and Ferrarese et al. (2006b). The straight line is the same as that shown in Fig. 1, and the curved line is the same as that shown in Fig. 2.