IR-derived covering factors for a large sample of quasars from WISE-UKIDSS-SDSS

I. G. Roseboom, A. Lawrence, M. Elvis, S. Petty, Yue Shen, H. Hao

Research output: Contribution to journalArticle


We investigate the range of covering factors (determined from the ratio of IR to UV/optical luminosity) seen in luminous type 1 quasars using a combination of data from the Wide- Field Infrared Survey Explorer, UKIDSS and SDSS surveys. Accretion disc (UV/optical) and obscuring dust (IR) luminosities are measured via the use of a simple three-component SED model. We use these estimates to investigate the distribution of covering factors and its relationship to both accretion luminosity and IR SED shape. The distribution of covering factors (fC) is observed to be log-normal, with a bias-corrected mean of <log10 fC ≥-0.41 and standard deviation of σ = 0.2. The fraction of IR luminosity emitted in the near-IR(1-5 μm) is found to be high (~40 per cent), and strongly dependant on covering factor.

Original languageEnglish (US)
Pages (from-to)1494-1501
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Feb 25 2013
Externally publishedYes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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