The role of black holes and their capacity to liberate large amounts of energy during their growth phases remains one of the thorniest issues in extragalactic astrophysics. While we are approaching a fairly complete census of black hole growth and host galaxy properties in the local universe, the high redshift universe remains only partially explored as low-luminosity and heavily-obscured AGN remain elusive in even the deepest surveys. Recent observational advances point to an increasing importance of secular processes in feeding black hole growth and to multiple, distinct pathways to black hole feeding. Thus, the answer to question 1 is that there are a number of very different points along the evolutionary pathways of galaxies during which black hole growth occurs.
The evidence for feedback remains conflicting and may well be limited to very specific phases of galaxy evolution, such as spheroid formation. The possibility that feedback is kinetic in form driven by radiatively inefficient black hole growth remains attractive. Despite this it remains poorly explored in the galaxy regime. Thus, question 2 remains more complex, though answers may be forthcoming in the near future. In particular, direct observations of black hole feedback on molecular gas reservoirs using the Atacama Large Millimeter Array (ALMA) will likely be revealing.
Present-day facilities such as Chandra and Hubble, combined with the next generation of near-infrared spectrographs on 8-10m telescopes, will continue to inform our picture of galaxy and black hole growth at high redshift as first glimpses of the earliest phases of both start to come into view (Treister et al. 2011), though fully understanding the black hole - galaxy connection all the way to the first objects in the universe may require the James Webb Space Telescope.
I am grateful for the Bash `11 Symposium organizers at the University of Austin - Texas for inviting me and for organizing such a wonderful meeting and I thank Ezequiel Treister and Meg Urry for comments. I acknowledge support by NASA through an Einstein Postdoctoral Fellowship (PF9-00069), issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060.