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Massive black holes in the young and old Universe
My research focuses mainly on exploring a formation route for the assembly of million solar masses black holes in the center of galaxies, and their connection to the evolution of cosmic structures and the high redshift universe.
Our present knowledge is still limited. We know that stellar-mass black holes form as endpoints of the evolution of massive stars. We also have found evidence of another, more exotic class of black holes: dark objects whose masses exceed millions, even billions, of solar masses. These intriguing systems have been nicknamed supermassive black holes, or SMBHs for short.
SMBHs might be black, but they are far from invisible. The first clue for their existence dates back to the sixties, and it was indirect evidence, through identification of quasars and active galactic nuclei, both in local and in high-redshift galaxies (i.e., when the Universe was very young). The huge power outputs from these tiny sources can be explained only as energy radiated away by matter falling into a SMBH: a direct application of the E=mc2 law.
Recently, evidence of SMBHs has been found in nearby galaxies, even where there are no signs of powerful activity. Their existence has been inferred from the orbits of stars and gas in the innermost regions, whose dynamics can be explained only by the deep gravitational field of a SMBH. The stars are seen to be moving too fast in the potential generated by the luminous matter alone: a massive object must be lurking in the depths, directing the movements of these puppet-stars.
My current research is aimed at developing a self-consistent theoretical scheme for the assembly of SMBHs and new observational diagnostics to probe it. My research is directed towards two main goals: understanding the dynamical and accretion processes around black holes, and their cosmological evolution.
- Evolution of massive black holes
- To appear in "2007 STScI Spring Symposium: Black Holes", eds. M. Livio & A. M. Koekemoer. (Cambridge University Press)