The bolometric output and host-galaxy properties of obscured AGN in the XMM-COSMOS survey

E. Lusso, A. Comastri, C. Vignali, G. Zamorani, E. Treister, D. Sanders, M. Bolzonella, A. Bongiorno, M. Brusa, F. Civano, R. Gilli, V. Mainieri, P. Nair, M. C. Aller, M. Carollo, A. M. Koekemoer, A. Merloni, J. R. Trump

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

We present a study of the multi-wavelength properties, from the mid-infrared to the hard X-rays, of a sample of 255 spectroscopically identified X-ray selected type-2 AGN from the XMM-COSMOS survey. Most of them are obscured and the X-ray absorbing column density is determined by either X-ray spectral analyses (for 45% of the sample), or from hardness ratios. Spectral energy distributions (SEDs) are computed for all sources in the sample. The average SEDs in the optical band are dominated by the host-galaxy light, especially at low X-ray luminosities and redshifts. There is also a trend between X-ray and mid-infrared luminosity: the AGN contribution in the infrared is higher at higher X-ray luminosities. We calculate bolometric luminosities, bolometric corrections, stellar masses and star formation rates (SFRs) for these sources using a multi-component modeling to properly disentangle the emission associated to stellar light from that due to black hole accretion. For 90% of the sample we also have the morphological classifications obtained with an upgraded version of the Zurich estimator of structural types (ZEST+). We find that on average type-2 AGN have lower bolometric corrections than type-1 AGN. Moreover, we confirm that the morphologies of AGN host-galaxies indicate that there is a preference for these type-2 AGN to be hosted in bulge-dominated galaxies with stellar masses greater than 1010 solar masses.

Original languageEnglish
Article numberA110
JournalAstronomy and Astrophysics
Volume534
DOIs
StatePublished - 2011

Scopus Subject Areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Galaxies: active
  • Galaxy: general
  • Methods: statistical
  • Quasars: general
  • X-rays: general

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