AGNPROBES

Active Galactic Nuclei as probes of galaxy evolution

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 Obiettivo del progetto (Objective)

'An important question facing modern astrophysics concerns the formation and evolution of galaxies. Supermassive black holes reside at the centers of galaxies and are intimately linked to how galaxies form and evolve. Massive galaxies form by merging of smaller gas-rich galaxies, and the central supermassive black hole grows by accretion of gas and dust, material that also feeds a nuclear starburst. With sufficient fuel the black hole grows rapidly until it reaches an accretion luminosity powerful enough to expel gas and dust from the nuclear regions. Both the black hole and the galaxy bulge end up being starved of building material by the very same feedback process. Thus black holes and bulges evolve to similar mass ratios. As end products of galaxy evolution local massive galaxies show exactly this behaviour, known as the M-sigma relation; The mass of the black hole correlates with the velocity dispersion of stars in the bulge (the bulge potential). The origin of the black hole-bulge connection is still largely unknown and the physical details of the black hole feedback process is not known at all, it is included in models merely as a separate recipe. Models are in dire need of observational input. If models are correct, we expect to see some galaxies, perhaps at larger look-back times, that do not have a black hole-bulge mass ratio corresponding to that of local galaxies. This proposal will use galaxies with actively accreting supermassive black holes (AGN) to address the need for observational data at larger look-back times. AGN are not only the best probes for investigating the black hole-bulge connection in the more distant Universe, but also the only ones, because it is via black hole activity in AGN that we can estimate black hole masses. Central to the project is the use of the new state-of-the-art X-shooter instrument on the European Southern Observatory's Very Large Telescope, on which the NBI Dark Cosmology Group has guaranteed time in 2009.'

Introduzione (Teaser)

One of the unsolved mysteries in modern observational astrophysics is the role of supermassive black holes in the evolution of galaxies. Although their existence at the centre of galaxies has been established only recently the impact they have on their host galaxies was elucidated by EU-funded scientists.