Seyfert galaxies with strong Fe II emission

Journal Article · Sun Aug 01 04:00:00 EDT 1976 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/154540· OSTI ID:7356379

Oke, J B; Shields, G A

Spectral energy distributions of the Seyfert galaxies Zw 2130+09 (=II Zw 136) and Zw 0051+12 (=I Zw 1) and the QSO 3C 273 have been measured over the wavelength interval lambdalambda3300--10500 with a resolution of approx.50 A. The objects all have broad permitted emission lines of H I, He I, Fe II, and O I; Zw 2130+09 also has narrow forbidden lines. The permitted line intensities are consistent with a filamentary emission region having N/sub e/approx. =10/sup 9/ cm/sup -3/, Rapprox. =1 pc, Mapprox. =10/sup 2/ M/sub sun/, and ..nu..approx. =3000 km s/sup -1/. On the assumption of photoionization, the observed H..beta.. intensities are smaller than expected on the basis of an extrapolation of the visual continua to ionizing frequencies, and this suggests that the emission-line region does not completely surround the continuum source or that the continuum slope becomes steeper for lambda<3000 A. The Fe II line intensities can be explained by continuum fluorescence if the observed line widths result from radial rather than circular motion. The derived column density is approx.10/sup 23plus-or-minus/ cm/sup -2/, comparable to the value implied by the X-ray absorption in NGC 4151. The O I lambda8446 emission may result from continuum fluorescence; alternatively, it can be explained by L..beta.. fluorescence if a portion of the broad line region has tau (H..cap alpha..) >100 as a result of time-dependent ionization. A picture in which both the O I and Fe II emission results from continuum fluorescence in an outer, optically thick H/sup 0/ zone is favored by (1) the absence of FeIII emission and (2) the large value expected for ..integral..N (O/sup 0/) dl/ ..integral..N (Fe/sup +/) dl. (AIP)

• Research Organization: Hale Observatories, California Institute of Technology, Carnegie Institution of Washington
• OSTI ID: 7356379
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 207:3; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics &amp; Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC RADIO SOURCES
EMISSION SPECTRA
ENERGY-LEVEL TRANSITIONS
EXCITATION
GALAXIES
IONIZATION
LINE WIDTHS
LYMAN LINES
PHOTOIONIZATION
QUASARS
SEYFERT GALAXIES
SPECTRA