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The Space Density of High-Redshift QSOs in the GOODS Survey

S. Cristiani·D. M. Alexander·F. Bauer·W. N. Brandt·E. T. Chatzichristou·F. Fontanot·A. Grazian·A. Koekemoer·R. A. Lucas·P. Monaco·M. Nonino·P. Padovani·D. Stern·P. Tozzi·E. Treister·C. M. Urry·E. Vanzella
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Abstract

We present a sample of 17 high-redshift (3.5<z<5.2) QSO candidates in the 320 sq.arcmin area of the Great Observatories Origins Deep Survey, selected in the magnitude range 22.45<z_{850}<25.25 using deep imaging with the Advanced Camera for Surveys onboard the Hubble Space Telescope and the Advanced CCD Imaging Spectrometer onboard the Chandra X-ray Observatory. On the basis of seven spectroscopic and ten photometric redshifts we estimate that the final sample will contain between two and four QSOs with 4<z<5.2. A dearth of high-redshift, moderate-luminosity (M_{145}=~-23) QSOs is observed with respect to predictions based on a) the extrapolation of the z~2.7 luminosity function (LF), according to a pure luminosity evolution calibrated by the results of the Sloan Digital Sky Survey; and b) a constant universal efficiency in the formation of super-massive black holes (SMBHs) in dark-matter halos. Evidence is gathered in favor of a density evolution of the LF at high redshift and of a suppression of the formation or feeding of SMBHs in low-mass halos.

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S. Cristiani, D. M. Alexander, F. Bauer, W. N. Brandt, E. T. Chatzichristou, F. Fontanot, A. Grazian, A. Koekemoer, R. A. Lucas, P. Monaco, M. Nonino, P. Padovani, D. Stern, P. Tozzi, E. Treister, C. M. Urry, E. Vanzella. 2003-09-02. The Space Density of High-Redshift QSOs in the GOODS Survey. https://doi.org/10.1086/378788

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