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Paper: z ∼ 6 Quasars from the Sloan Digital Sky Survey
Volume: 311, AGN Physics with the Sloan Digital Sky Survey
Page: 431
Authors: Fan, X.; Strauss, M.A.; Richards, G.T.; Gunn, J.E.; Lupton, R.H.; Schneider, D.P.; Pentericci, L.; Rix, H.-W.; the SDSS Collaboration
Abstract: We present the recent results on a survey for quasars at z ~ 6, selected from ~ 3000 deg2 of multicolor imaging data from the Sloan Digital Sky Survey (SDSS). Seven luminous (M ~ −27) quasars at 5.7 < z < 6.4 are discovered. The existence of strong metal lines in the quasar spectra suggests early metal enrichment in the quasar environment. These quasars, if not gravitationally lensed, are located in supermassive black holes of M ~ 109-10 MSolar, indicating rapid formation of supermassive black hole population in the early universe, probably co-eval with the formation of the first generation galaxies. A number of z~ 6 quasars show strong dust and gas emission in sub-millimeter and radio wavelengths, further indicating close ties to the early star-formation activity in their host galaxies. We find that at z = 6, the comoving density of luminous quasars declines by a factor of ~ 20 from z ~ 3. The observations of quasar luminosity function will put strong constraint on the models of black hole evolution.
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