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Paper: Star Formation and Interstellar Medium in the Most Distant AGNs
Volume: 408, The Starburst−AGN Connection
Page: 235
Authors: Maiolino, R.
Abstract: I will discuss some recent results on the interstellar medium and star formation in the host galaxies of very high redshift AGNs, close to the reionization epoch. I will first discuss evidences that the gas in high-z AGN hosts is metal rich, with no evidence for any redshift evolution. I will show that both the high metallicity and the lack of evolution are probably a consequence a combination of selection effects and of the black hole-galaxy coevolution. However, the data also suggest a lack of evolution of the carbon abundance, even among z>6 quasars; this result is puzzling, since the minimum enrichment timescale of carbon is about 1 Gyr, i.e. longer than the age of the universe at z~6. Millimeter observations show that these high-z AGNs are characterized by vigorous star formation, which is likely responsible for the high and rapid metal enrichment in these AGN hosts. Thanks to high resolution millimetric observations, we could resolve the starburst in one of these distant quasars and inferring an extremely high density of star formation, probably tracing the rapid formation of a massive bulge. High angular resolution millimetric observations also allow us to estimate the dynamical mass of a few high-z quasar hosts at 4<z<6.4. The inferred MBH − Mgalaxy relation at high-z is offset by about an order of magnitude, in terms of BH mass, relative to the local relation, suggesting that at high redshift black holes form faster than their host galaxies.
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