A theoretical and observational analysis of He I triplet lines in class 1 Seyfert galaxy spectra

Feldman, F. R.; MacAlpine, G. M.

doi:10.1086/156050

Cited by 10 publications

(5 citation statements)

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“…Broad He I emission lines are observed in AGNs: λ3188 (Baldwin et al 1980), λ4471 (van Groningen & de Bruyn 1989Feldman & MacAlpine 1978), λ5876 and λ7065 (Feldman & MacAlpine 1978;Morris & Ward 1988) and λ10830 (LeVan et al 1984). The He I lines at λ4471, λ4922, λ5016, λ5876 and λ6678 have been detected in the NLS1 galaxy Mark 110 (Kollatschny et al 2001).…”

Section: He I λ4922 and λ5016mentioning

confidence: 94%

“…Broad He I emission lines are observed in AGNs: λ3188 (Baldwin et al 1980), λ4471 (van Groningen & de Bruyn 1989Feldman & MacAlpine 1978), λ5876 and λ7065 (Feldman & MacAlpine 1978;Morris & Ward 1988) vidual components (Hβ and He I λλ4922,5016). A number of narrow emission lines have been identified, many of them being due to iron.…”

Section: He I λ4922 and λ5016mentioning

confidence: 99%

“…The broad He I λ4471 line is usually weak in Seyfert 1s (λ4471/λ5876∼0.1) implying n e ∼10 9 cm −3 (Feldman & MacAlpine 1978;Almog & Netzer 1989). concluded that the λ5016 line emission could contribute only a small fraction of the "red shelf" observed in Seyfert 1s; this statement was based on the assumption that λ5016 should not be stronger than λ6678 and that the strength of this last line is typically 0.6-0.8% of that of Hα.…”

Section: He I λ4922 and λ5016mentioning

confidence: 99%

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The “red shelf" of the H$\boldmath\beta$ line in the Seyfert 1 galaxies RXS J01177+3637 and HS 0328+05

Véron

Gonçalves

Véron-Cetty

2002

A&A

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Abstract. A few Seyfert 1s have a Hβ profile with a red wing usually called the "red shelf". The most popular interpretation of this feature is that it is due to broad redshifted lines of Hβ and [O III]λλ4959, 5007; we have observed two Seyfert 1s displaying a "red shelf" and showed that in these two objects the main contributor is most probably the He I λλ4922, 5016 lines having the velocity and width of the broad Hβ component. There is no evidence for the presence of a broad redshifted component of Hβ or [O III] in any of these two objects.

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Section: He I λ4922 and λ5016mentioning

confidence: 94%

“…Broad He I emission lines are observed in AGNs: λ3188 (Baldwin et al 1980), λ4471 (van Groningen & de Bruyn 1989Feldman & MacAlpine 1978), λ5876 and λ7065 (Feldman & MacAlpine 1978;Morris & Ward 1988) vidual components (Hβ and He I λλ4922,5016). A number of narrow emission lines have been identified, many of them being due to iron.…”

Section: He I λ4922 and λ5016mentioning

confidence: 99%

Section: He I λ4922 and λ5016mentioning

confidence: 99%

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The “red shelf" of the H$\boldmath\beta$ line in the Seyfert 1 galaxies RXS J01177+3637 and HS 0328+05

Véron

Gonçalves

Véron-Cetty

2002

A&A

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“…The Balmer line FWHM lies in the range 1 760-2 300 km s −1 (Osterbrock 1977a;Feldman & MacAlpine 1978;Phillips 1978a;Peterson et al 1982;Boroson & Meyers 1992); it is a relatively strong Fe II emitter with R 4570 = 0.50 (Boroson & Meyers 1992). It has however been classified as a Seyfert 1 rather than an NLS1 by Moran et al (1996).…”

Section: Notes On Individual Objectsmentioning

confidence: 99%

A spectrophotometric atlas of Narrow-Line Seyfert 1 galaxies

Véron-Cetty

Véron

Gonçalves³

2001

A&A

285

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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“…For example, the integral cross section u2,3 is important in primordial nucleosynthesis 0953-4075/90/244573+32$03.50 @ 1990 IOP Publishing Ltd (Ferland 1986)) and in the interpretation of the spectra of Seyfert galaxies (Feldman and MacAlpine 1978)) as well as in the stepwise ionization of helium atoms in gaseous discharges.…”

Section: Introductionmentioning

confidence: 99%

The multichannel eikonal theory of electron-helium collisions. I. Excitation of He(1¹S)

Mansky¹,

Flannery²

1990

J. Phys. B: At. Mol. Opt. Phys.

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Calculations of the integral and differential cross sections for the electronic excitation of the 2'L and 3lL states of helium are reported. The multichannel eikonal theory employing a 10-channel basis set is used. The X and x parameters for the 2'P and 3 l P states at 80 eV are also reported. A number of misprints concerning the original multichannel eikonal theory results of Flannery and McCann have occurred in the literature. These misprints are corrected in this paper. A detailed description of both the theoretical and experimental difficulties involved in the determination of the integral cross sections 01is,31s and 0 1 ~s , 3 ~D is provided. In addition, a critique of the assumptions made in previous experimental determinations of the differential cross sections (both composite and magnetic sublevel) for the 3IL states of helium is given. A result of this analysis is that the experimental data on the differential cross sections for the 3'P state need to be re-interpreted in light of the experimental data of van Linden van den Heuvell e t al. A principal conclusion of this paper is that the first Born approximation undecestimates experimental data in the intermediate energy region for 'S -+ ID transitions, in contrast to the trend seen in 'S --t 'P transitions. The reason for such a reversal in I S i 'D transitions can be understood in terms of the direct (i -+ j ) , and indirect (i i n --+ j , etc) mechanisms which are important in the electronic excitation of the 3l L states of He.In particular, in this paper the importance of indirect mechanisms in the excitation of the 3IS and 3ID is shown, thereby confirming the early results of Churig and Lin and the tentative conclusions of Massey.

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A theoretical and observational analysis of He I triplet lines in class 1 Seyfert galaxy spectra

Cited by 10 publications

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The “red shelf" of the H$\boldmath\beta$ line in the Seyfert 1 galaxies RXS J01177+3637 and HS 0328+05

The “red shelf" of the H$\boldmath\beta$ line in the Seyfert 1 galaxies RXS J01177+3637 and HS 0328+05

A spectrophotometric atlas of Narrow-Line Seyfert 1 galaxies

The multichannel eikonal theory of electron-helium collisions. I. Excitation of He(1¹S)

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A theoretical and observational analysis of He I triplet lines in class 1 Seyfert galaxy spectra

Cited by 10 publications

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The “red shelf" of the H$\boldmath\beta$ line in the Seyfert 1 galaxies RXS J01177+3637 and HS 0328+05

The “red shelf" of the H$\boldmath\beta$ line in the Seyfert 1 galaxies RXS J01177+3637 and HS 0328+05

A spectrophotometric atlas of Narrow-Line Seyfert 1 galaxies

The multichannel eikonal theory of electron-helium collisions. I. Excitation of He(11S)

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The multichannel eikonal theory of electron-helium collisions. I. Excitation of He(1¹S)