The luminosity dependence of ultraviolet absorption in active galactic nuclei

Ari Laor, W. N. Brandt

Research output: Contribution to journalReview article

91 Scopus citations

Abstract

We describe the results of a survey of the UV absorption properties of the Boroson & Green sample of active galactic nuclei (AGNs), which extends from the Seyfert (MV ≃ -21) to the luminous quasar (MV ≃ -27) level. The survey is based mostly on Hubble Space Telescope archival data available for ≳1/2 of the 87 sample objects. Our main result is that soft X-ray-weak quasars (SXWQs; 10 AGNs with αox ≤ -2) show the strongest UV absorption at a given luminosity, and their maximum outflow velocity, νmax, is strongly correlated with MV (rS = -0.95). This suggests that νmax is largely set by the luminosity, as expected for radiation pressure-driven outflows. Luminous SXWQs have preferentially low [O III] luminosity, which suggests that they are physically distinct from unabsorbed AGNs, while non-SXWQs with UV absorption are consistent with being drawn from the unabsorbed AGN population. We also find an indication that νmaxBLR increases with L/LEdd, as expected for radiation pressure-driven outflows. This relation and the νmax versus MV relation may indicate that the radiation-pressure force multiplier increases with luminosity and that the wind-launching radius in non-SXWQs is ∼10 times larger than in SXWQs.

Original languageEnglish (US)
Pages (from-to)641-654
Number of pages14
JournalAstrophysical Journal
Volume569
Issue number2 I
DOIs
StatePublished - Apr 20 2002

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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