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C. M. Urry, E. Treister, E. T. Chatzichristou, J. Van Duyne (Yale University), F. E. Bauer, D. M. Alexander (IoA Cambridge), A. M. Koekemoer, L. A. Moustakas (STScI), W. N. Brandt (Penn State), N. A. Grogin (JHU), J. Bergeron (IAP Paris), D. Stern (JPL/Caltech), R.-R. Chary (SSC/Caltech), C. J. Conselice (Caltech), S. Cristiani (Obs. Astr. Trieste)
We model the X-ray, optical, and far-infrared flux distributions of AGN in the GOODS fields, starting from hard X-ray luminosity functions and spectral energy distributions appropriate to the unified scheme for AGN. The deep optical counts measured from HST ACS images can be well explained by a unified scheme that postulates roughly 3 times as many obscured as unobscured AGN. This scenario is consistent with the observed spectroscopic and photometric redshift distributions of the GOODS AGN once selection effects are considered. The previously reported discrepancy between observed spectroscopic redshift distributions and the predictions of population synthesis models for the X-ray background (which include a similarly large number of obscured AGN) is explained by bias against the most heavily obscured AGN in both X-ray surveys and optical spectroscopic samples. We present the model predictions for the number counts of AGN in the Spitzer MIPS 24 micron and IRAC 3.6-8 micron bands. The GOODS Spitzer observations will verify whether large numbers of obscured AGN are indeed present in the early Universe; these will be very bright far-infrared sources, including some, missed by X-ray observations, that look like ultraluminous infrared galaxies.
Based on observations obtained with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc, under NASA contract NAS5-26555. This work was supported by NASA grants HST-GO-09425(.01-A,.13-A,.26-A); NSF CAREER award AST 99-83783; NASA contract number 1224666 issued by JPL/Caltech under NASA contract 1407; ASI grant I/R/088/02; and a Royal Society University Research Fellowship.
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Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.