Galaxy Formation in Triaxial Halos: Black Hole-Bulge-Dark Halo Correlation

Abstract

The masses of supermassive black holes (SBHs) show correlations with bulge properties in disk and elliptical galaxies. We study the formation of galactic structure within flat-core triaxial haloes and show that these correlations can be understood within the framework of a baryonic component modifying the orbital structure in the underlying potential. In particular, we find that terminal properties of bulges and their central SBHs are constrained by the destruction of box orbits in the harmonic cores of dark haloes and the emergence of progressively less eccentric loop orbits there. SBH masses, M_SBH, should exhibit a tighter correlation with bulge velocity dispersions, sigma_B, than with bulge masses, M_B, in accord with observations, if there is a significant scatter in the M_H-sigma_H relation for the halo. In the context of this model the observed M_SBH-sigma_B relation implies that haloes should exhibit a Faber-Jackson type relationship between their masses and velocity dispersions. The most important prediction of our model is that halo properties determine the bulge and SBH parameters. The model also has important implications for galactic morphology and the process of disk formation.