The structures of galaxies, and the evolution of structures, potentially relates directly with the existence of dark matter, dark energy and black holes. I only briefly discuss this here as much of this is work for the future. One example is that galaxy mergers might not occur as commonly without the dynamical friction produced by dark matter halos (e.g., Sellwood 2004). Detailed modeling of this however has not yet been done. As discussed, black holes are directly traceable with the concentration of galaxy light (Section 2). Dark energy is also likely imprinting its effects, and is perhaps the fundamental cause of the morphology-redshift relationship.
The relationship between the velocity dispersion of spheroids and the mass of their central black holes (Gebhardt et al. 2000; Ferrarese & Merritt 2000) is a fundamental property of spheroids. This relationship, which is effectively between the scale of a spheroid system and its central black hole, is also projected in the concentration index-black hole mass relationship. This relationship appears to hold to some degree up to z ~ 1.2 based on the correlation between galaxies with X-ray emission and the CAS concentration index (Grogin et al. 2003). X-ray sources up to z ~ 1.2 are found in galaxies with the highest light concentrations, suggesting that the bulge/central black hole relationship is in place by these redshifts. Understanding this relationship at higher redshift, as well as how dark matter condenses and evolves with galaxy structure, are topics for future investigations with 20-30 meter ground based telescopes and the James Webb Space Telescope.
It is a pleasure to acknowledge my collaborators and colleagues, especially Mark Dickinson, Richard Ellis, Kevin Bundy, and Casey Papovich for helping shape my evolving understanding of this material. Thanks also to Colin Borys and Kevin Bundy for comments on this manuscript. I also thank David Block and the organizing committees for inviting me to present this contribution and their patience in receiving this review.