Observations of the H-beta region in some broad-line objects

Robertis, M. De

doi:10.1086/162865

Cited by 44 publications

(23 citation statements)

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“…The Hβ FWHM is in the range 1050-1500 km s −1 (Osterbrock 1977a;Phillips 1978a;Peterson et al 1982;de Robertis 1985) although Wilkes et al (1999) measured 2590 km s −1 . The broad Balmer components clearly have a complex and asymmetrical profile; to get a satisfactory fit of our spectra, two Lorentzians were needed.…”

Section: Notes On Individual Objectsmentioning

confidence: 92%

“…Mark 486 (1535+54). The Hβ FWHM is in the range 1410-1650 km s −1 (Boroson & Green 1992;de Robertis 1985;Osterbrock & Shuder 1982;Boroson et al 1985). The Fe II emission is relatively strong (Phillips 1978a).…”

Section: Mark 705 (0923+12)mentioning

confidence: 95%

“…The broad Balmer lines exhibit a wide variety of profile shapes and a large range in width (Osterbrock & Shuder 1982;de Robertis 1985;Crenshaw 1986;Stirpe 1991;Miller et al 1992); they are often strongly asymmetric (Corbin 1995). The BLR consists of two components: one Intermediate Line Region (ILR) with line width ∼2000 km s −1 FWHM, with the peak within a few hundred kilometers per second of the systemic redshift, and a Very Broad Line Region (VBLR) with lines of width >7000 km s −1 and blueshifted by more than 1000 km s −1 ; differences in the relative strengths of these components account for much of the diversity of broad line profiles (Wills et al 1993;Brotherton et al 1994;Corbin 1995Corbin , 1997Francis et al 1992).…”

Section: High-and Low-ionization Linesmentioning

confidence: 99%

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A spectrophotometric atlas of Narrow-Line Seyfert 1 galaxies

Véron-Cetty

Véron

Gonçalves³

2001

A&A

283

324

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Abstract.We have compiled a list of 83 objects classified as Narrow-Line Seyfert 1 galaxies (NLS1s) or known to have a broad Balmer component narrower than 2 000 km s −1 . Of these, 19 turned out to have been spectroscopically misidentified in previous studies; only 64 of the selected objects are genuine NLS1s. We have spectroscopically observed 59 of them and tried to characterize their Narrow and Broad-Line Regions (NLR and BLR) by fitting the emission-lines with Gaussian and/or Lorentzian profiles. In most cases, the broad Balmer components are well fitted by a single Lorentzian profile, confirming previous claims that Lorentzian rather than Gaussian profiles are better suited to reproduce the shape of the NLS1s broad emission lines. This has consequences concerning their FWHMs and line ratios: when the broad Balmer components are fitted with a Lorentzian, most narrow line regions have line ratios typical of Seyfert 2s while, when a Gaussian profile is used for fitting the broad Balmer components, the line ratios are widely scattered in the usual diagnostic diagrams (Veilleux & Osterbrock 1987); moreover, the FWHM of the best fitting Lorentzian is systematically smaller than the FWHM of the Gaussian. We find that, in general, the [O III] lines have a relatively narrow Gaussian profile (∼200-500 km s −1 FWHM) with often, in addition, a second broad (∼500-1 800 km s −1 FWHM), blueshifted Gaussian component. We do not confirm that the [O III] lines are weak in NLS1s. As previously suggested, there is a continuous transition of all properties between NLS1s and classical Broad-Line Seyfert 1 Galaxies (BLS1s) and the limit of 2000 km s −1 used to separate the two species is arbitrary; R4570, the ratio of the Fe II to the Hβ fluxes, could be a physically more meaningful parameter to distinguish them.

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Section: Notes On Individual Objectsmentioning

confidence: 92%

Section: Mark 705 (0923+12)mentioning

confidence: 95%

Section: High-and Low-ionization Linesmentioning

confidence: 99%

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A spectrophotometric atlas of Narrow-Line Seyfert 1 galaxies

Véron-Cetty

Véron

Gonçalves³

2001

A&A

283

324

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“…The virial assumption is not likely to be generally valid for the emission line gas in AGNs. It has been known for several decades that different emission lines in a source can show different width and profile shape (e.g., de Robertis 1985;Sulentic 1989). The virial assumption implies that the velocity dispersion will steadily decrease with distance from the central black hole ∝r − 1 2 .…”

Section: Introductionmentioning

confidence: 99%

“…This implies that deviations from a symmetric profile can affect M BH estimates by ≈40%. Uncertainties are also introduced by: (1) contamination from overlapping/nearby lines such as Feii, Heiiλ4686, and [Oiii]λλ4959,5007 (Osterbrock & Shuder 1982;de Robertis 1985;Joly 1988;Jackson et al 1991), (2) FWHM measures based on single-epoch observations, (3) low S /N spectra and (4) spectra without Hβ narrow component (Hβ NC ) subtraction. The r BLR -L λ relation is also not free from uncertainties.…”

Section: Introductionmentioning

confidence: 99%

VLT/ISAAC spectra of the Hβregion in intermediate-redshift quasars

Sulentic¹,

Repetto

Stirpe³

et al. 2006

A&A

110

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We derive black hole masses for a sample of about 300 AGNs in the redshift range 0 < z < 2.5. We use the same virial velocity measure (FWHM Hβ BC ) for all sources which represents a significant improvement over previous studies. We review methods and caveats for determining AGN black hole masses via the virial assumption for motions in the gas producing low ionization broad emission lines. We derive a corrected FWHM(Hβ BC ) measure for the broad component of Hβ that better estimates the virialized line emitting component by comparing our FWHM measures with a sample of reverberated sources with Hβ radial velocity dispersion measures. We also consider the FWHM of the Feiiλ4570 blend as a potential alternative velocity estimator. We find a range of black hole mass between log M BH ∼ 6.0-10.0, where M BH is in solar masses. Estimates using corrected FWHM(Hβ), as well as FWHM (Feii) measures, reduce the number of sources with log M BH > 9.5 and suggest that extremely large M BH values (log M BH > ∼ 10) may not be realistic. Derived L/L Edd values show no evidence for a significant population of super-Eddington radiators especially after correction is made for sources with extreme orientation to our line of sight. Sources with FWHM(Hβ BC ) < ∼ 4000 km s −1 show systematically higher L/L Edd and lower M BH values than broader lined AGNs (including almost all radio-loud sources).

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Emission-line spectra and the nature of active galactic nuclei

Osterbrock

Active Galactic Nuclei

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Observations of the H-beta region in some broad-line objects

Cited by 44 publications

References 0 publications

A spectrophotometric atlas of Narrow-Line Seyfert 1 galaxies

A spectrophotometric atlas of Narrow-Line Seyfert 1 galaxies

VLT/ISAAC spectra of the Hβregion in intermediate-redshift quasars

Emission-line spectra and the nature of active galactic nuclei

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