The DOI matches its Crossref record; 24 of the 24 references it cites were found in a registry or an index.
What controls the C iv line profile in active galactic nuclei?
Open accessAbstract
The high-ionization lines in active galactic nuclei (AGN), such as C iv, tend to be blueshifted with respect to the lower-ionization lines, such as Hβ, and often show a strong blue excess asymmetry not seen in the low-ionization lines. There is accumulating evidence that the Hβ profile is dominated by gravity, and thus provides a useful estimate of the black hole mass in AGN. The shift and asymmetry commonly seen in C iv suggest that non-gravitational effects, such as obscuration and radiation pressure, may affect the line profile. We explore the relation between the Hβ and C iv profiles using the ultraviolet (UV) spectra available for 81 of the 87 z≤ 0.5 PG quasars in the Boroson & Green sample. We find the following. (1) Narrow C iv lines (full width at half-maximum, FWHM < 2000 km s−1) are rare (∼2 per cent occurrence rate) compared with narrow Hβ lines (∼20 per cent). (2) In most objects where the Hβ FWHM < 4000 km s−1 the C iv line is broader than Hβ, but the reverse is true when the Hβ FWHM > 4000 km s−1. This argues against the view that C iv generally originates closer to the centre, compared with Hβ. (3) C iv appears to provide a significantly less accurate, and possibly biased estimate of the black hole mass in AGN, compared with Hβ. (4) All objects where C iv is strongly blueshifted and asymmetric have a high L/LEdd, but the reverse is not true. This suggests that a high L/LEdd is a necessary but not sufficient condition for generating a blueshifted asymmetric C iv emission. (5) We also find indications for dust reddening and scattering in ‘normal’ AGN. In particular, PG quasars with a redder optical–UV continuum slope show weaker C iv emission, stronger C iv absorption and a higher optical continuum polarization.
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Cites
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The emission-line properties of low-redshift quasi-stellar objects
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Self-citationInterstellar extinction in the UV
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The spectra of narrow-line Seyfert 1 galaxies
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Self-citationBlack Hole Mass Estimates from Reverberation Mapping and from Spatially Resolved Kinematics
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Phenomenology of Broad Emission Lines in Active Galactic Nuclei
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Cited by
A CATALOG OF QUASAR PROPERTIES FROM SLOAN DIGITAL SKY SURVEY DATA RELEASE 7
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Active galactic nuclei: what’s in a name?
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Metadata
- Authors
- Baskin, A., & Laor, A.
- Venue
- Monthly Notices of the Royal Astronomical Society
- Publisher
- Oxford University Press (OUP)
- Published
- 2005-01
- Volume
- 356
- Issue
- 3
- Pages
- 1029-1044
- ISSN
- 0035-8711 (ISSN-L)
- 1365-2966
- OpenAlex
- W2016662888
- Cited by
- 258
- References
- 24
- FWCI
- 8.00
- Type
- journal article
- Language
- en
- Open access
- green
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