Emission-line widths in galactic nuclei

Feldman, F. R.; Weedman, D. W.; Balzano, V.; Ramsey, Lawrence W.

doi:10.1086/159919

Cited by 41 publications

(25 citation statements)

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“…The Hβ line ratio of these two systems is 0.20. The intrinsic [O III]λ5007 FWHM is equal to 280 ± 3 km s −1 (Feldman et al 1982) or 288 ± 5 km s −1 (Vrtilek & Carleton 1985). The resolution of our spectra is 475 km s Peterson et al (1998).…”

Section: The Narrow Line Systemmentioning

confidence: 89%

The optical emission line spectrum of Mark 110

Véron-Cetty

Véron

Joly³

et al. 2007

A&A

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Aims. We analyse in detail the rich emission line spectrum of Mark 110 to determine the physical conditions in the nucleus of this object, a peculiar NLS1 without any detectable Fe II emission associated with the broad line region and with a λ5007/Hβ line ratio unusually large for a NLS1. Methods. We use 24 spectra obtained with the Marcario Low Resolution Spectrograph attached at the prime focus of the 9.2 m HobbyEberly telescope at the McDonald observatory. We fitted the spectrum by identifying all the emission lines (about 220) detected in the wavelength range 4200−6900 Å (at rest). Results. The narrow emission lines are probably produced in a region with a density gradient in the range 10 3 −10 6 cm −3 with a rather high column density (5 × 10 21 cm −2 ). In addition to a narrow line system, three major broad line systems with different line velocity and width are required. We confirm the absence of broad Fe II emission lines. We speculate that Mark 110 is in fact a BLS1 with relatively "narrow" broad lines but with a BH mass large enough compared to its luminosity to have a lower than Eddington luminosity.

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Section: The Narrow Line Systemmentioning

confidence: 89%

The optical emission line spectrum of Mark 110

Véron-Cetty

Véron

Joly³

et al. 2007

A&A

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“…As mentioned earlier, asymmetries in the [O III] j5007 line have been extensively studied by Whittle (1985) and Heckman et al (1981). NGC 7674 contains a very strong blue asymmetry in its spectrum which has been studied extensively (e.g., Shuder & Osterbrock 1981 ;Feldman et al 1982 ;de Robertis & Osterbrock 1986 ;Veilleux 1991 ;Veilleux et al 1999). The blue asymmetry is has been tentatively linked to regions of high ionization/critical density (de Robertis & Shaw 1990).…”

Section: Blue Asymmetry Galaxiesmentioning

confidence: 92%

Optical Classification of Southern Warm Infrared Galaxies

Kewley

Heisler

Dopita

et al. 2001

ASTROPHYS J SUPPL S

444

611

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In this paper, we present high-resolution optical spectra and optical classiÐcations from our large sample of 285 warm infrared galaxiesWe have classiÐed these galaxies using new 108 \ L IR \ 1012.5 L _ . theoretical lines on the standard optical diagnostic diagrams. We use a theoretical extreme mixing line between the starburst and AGN regions to classify LINER galaxies and we deÐne a theoretical boundary separating AGNs from starbursts. We Ðnd that many galaxies previously classiÐed as LINERs appear to lie on a mixing sequence between starburst and AGN type galaxies. These are likely to be of a composite nature with their excitation being a combination of photoionization due to hot stars plus either ionization by a power-law radiation Ðeld associated with an AGN or shock excitation where the shock may result from such processes as cooling Ñows, superwind activity, or an accretion disk around an AGN. We compare our theory-based classiÐcation scheme with the previous semiempirical scheme of Veilleux & Osterbrock . We Ðnd that our classiÐcation method results in 6% ambiguity in classiÐcations between the di †erent diagnostic diagrams compared with 16% ambiguity using the traditional Veilleux & Osterbrock method. We Ðnd that 70% of the galaxies in our sample are classiÐed optically as starburst, 17% are Seyfert 2, 4% are Seyfert 1, and 0.4% are LINERs. A further 2% of our sample are certainly composite galaxies. A fraction (20%) of the Seyfert galaxies, 3% of the starburst galaxies, and 71% of the ambiguous galaxies are possibly composite in nature (11% of the total sample).

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“…Feldman et al 1982). The red spectral region contains the isolated Ca II absorption triplet, which can be used to estimate the central black hole mass.…”

Section: Optical Spectroscopymentioning

confidence: 99%

The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

Gandhi

Annuar

Lansbury

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present NuSTAR X-ray observations of the active galactic nucleus (AGN) in NGC 7674. The source shows a flat X-ray spectrum, suggesting that it is obscured by Compton-thick gas columns. Based upon long-term flux dimming, previous work suggested the alternate possibility that the source is a recently switched-off AGN with the observed X-rays being the lagged echo from the torus. Our high-quality data show the source to be reflection-dominated in hard X-rays, but with a relatively weak neutral Fe Kα emission line (equivalent width [EW] of ≈ 0.4 keV) and a strong Fe XXVI ionised line (EW ≈ 0.2 keV). We construct an updated longterm X-ray light curve of NGC 7674 and find that the observed 2-10 keV flux has remained constant for the past ≈ 20 years, following a high flux state probed by Ginga. Light travel time arguments constrain the minimum radius of the reflector to be ∼ 3.2 pc under the switchedoff AGN scenario, ≈ 30 times larger than the expected dust sublimation radius, rendering this possibility unlikely. A patchy Compton-thick AGN (CTAGN) solution is plausible, requiring a minimum line-of-sight column density (N H ) of 3 × 10 24 cm −2 at present, and yields an intrinsic 2-10 keV luminosity of (3-5) × 10 43 erg s −1 . Realistic uncertainties span the range of ≈ (1-13) × 10 43 erg s −1 . The source has one of the weakest fluorescence lines amongst bona fide CTAGN, and is potentially a local analogue of bolometrically luminous systems showing complex neutral and ionised Fe emission. It exemplifies the difficulty of identification and proper characterisation of distant CTAGN based on the strength of the neutral Fe Kα line.

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Emission-line widths in galactic nuclei

Cited by 41 publications

References 0 publications

The optical emission line spectrum of Mark 110

The optical emission line spectrum of Mark 110

Optical Classification of Southern Warm Infrared Galaxies

The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

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