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Obscured goods active galactic nuclei and their host galaxies at z <1.25: the slow black hole growth phase

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  • B. D. Simmons
  • J. Van Duyne
  • C. M. Urry
  • E. Treister
  • A. M. Koekemoer
  • N. A. Grogin
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Article number121
<mark>Journal publication date</mark>20/06/2011
<mark>Journal</mark>The Astrophysical Journal
Issue number2
Volume734
Number of pages16
Publication StatusPublished
<mark>Original language</mark>English

Abstract

We compute black hole masses and bolometric luminosities for 87 obscured active galactic nuclei (AGNs) in the redshift range 0.25 ≤ z ≤ 1.25, selected from the GOODS deep multi-wavelength survey fields via their X-ray emission. We fit the optical images and obtain morphological parameters for the host galaxy, separating the galaxy from its central point source, thereby obtaining a four-band optical spectral energy distribution (SED) for each active nucleus. We calculate bolometric luminosities for these AGNs by reddening a normalized mean SED of GOODS broad-line AGNs to match the observed central point-source SED of each obscured AGN. This estimate of L bol has a smaller spread than simple bolometric corrections to the X-ray luminosity or direct integration of the observed multi-wavelength SED, suggesting it is a better measure. We estimate central black hole masses from the bulge luminosities. The black hole masses span a wide range, 7 × 106 M ☉ to 6 × 109 M ☉; the median black hole mass is 5 × 108 M ☉. The majority of these AGNs have L/L Edd ≤ 0.01, and we detect no significant evolution of the mean Eddington ratio to z = 1.25. This implies that the bulk of black hole growth in these obscured AGNs must have occurred at z gsim 1 and that we are observing these AGNs in a slow- or no-growth state.