BAT AGN spectroscopic survey-II. X-ray emission and high-ionization optical emission lines

Simon Berney, Michael Koss*, Benny Trakhtenbrot, Claudio Ricci, Isabella Lamperti, Kevin Schawinski, Mislav Baloković, D. Michael Crenshaw, Travis Fischer, Neil Gehrels, Fiona Harrison, Yasuhiro Hashimoto, Kohei Ichikawa, Richard Mushotzky, Kyuseok Oh, Daniel Stern, Ezequiel Treister, Yoshihiro Ueda, Sylvain Veilleux, Lisa Winter

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

58 Citations (Scopus)


We investigate the relationship between X-ray and optical line emission in 340 nearby (z ≃ 0.04) AGN selected above 10 keV using Swift BAT. We find a weak correlation between the extinction corrected [O III] and hard X-ray luminosity (Lint[OIII] ∝ L14-195) with a large scatter (RPear = 0.64, σ = 0.62 dex) and a similarly large scatter with the intrinsic 2-10 keV to [OIII] luminosities (RPear = 0.63, s = 0.63 dex). Correlations of the hard X-ray fluxes with the fluxes of high-ionization narrow lines ([O III], He II, [NeIII] and [Ne V]) are not significantly better than with the low-ionization lines (H α, [SII]). Factors like obscuration or physical slit size are not found to be a significant part of the large scatter. In contrast, the optical emission lines show much better correlations with each other (σ = 0.3 dex) than with the X-ray flux. The inherent large scatter questions the common usage of narrow emission lines as AGN bolometric luminosity indicators and suggests that other issues such as geometrical differences in the scattering of the ionized gas or long-term AGN variability are important.

Original languageEnglish
Pages (from-to)3622-3634
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Publication statusPublished - 2015 Dec 21


  • Black hole physics
  • Galaxies: active
  • Galaxies: nuclei
  • Quasars: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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