Fe II and Fe i Emission in IRAS 07598+6508 and PHL 1092

Kwan, John; Cheng, F. H.; Fang, Li‐Zhi; Zheng, Wei; Ge, J.

doi:10.1086/175302

Cited by 28 publications

(35 citation statements)

References 15 publications

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“…In Figure 5, representing model u13h11, the predicted emission due to Fe i in the 2700-4500 8 region is, although quite weak, not entirely negligible. This is illustrated in the second panel from the top in Figure 5; the strongest transitions present in this figure are just those expected from the Fe i Grotrian diagram of Figure 1, namely decays from low-lying odd parity levels between $3.5 to 4.5 eV to the three lowest even parity states, the Kwan et al (1995) and in IRAS 07598+ 6508 by Kwan et al Both objects are Fe ii-strong quasars. The current calculations tend to support these identifications and the occurrence of Fe i transitions in some AGN spectra.…”

Section: Predicted Fe III Fluxesmentioning

confidence: 62%

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Theoretical Fei–iiiEmission‐Line Strengths from Active Galactic Nuclei with Broad‐Line Regions

Sigut

Pradhan

Nahar

2004

ApJ

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We present theoretical iron emission line strengths for physical conditions typical of active galactic nuclei (AGNs) with broad-line regions. The non-local thermodynamic equilibrium (NLTE) models include a new and extensive treatment of radiative transfer in the Fe iii ion, complementing the Fe ii emission line strengths predicted in our earlier works. We also briefly present preliminary results for the Fe i emission from AGNs using a reduced atom model. We can satisfactorily reproduce the empirical UV Fe iii emission line template of Vestergaard & Wilkes for the prototypical narrow-line Seyfert 1 galaxy I Zw 1, both in terms of the general Fe iii flux distribution and the relative strength of the Fe iii and Fe ii emission. However, a number of detailed features are still not matched; the most prominent example is the strongest single Fe iii feature observed in the I Zw 1 spectrum, UV47: it is predicted to be strong only in models suppressing Fe-H charge exchange reactions. We examine the role of variations in cloud turbulent velocity and iron abundance and carry out Monte Carlo simulations to demonstrate the effect of uncertainties in atomic data on the computed spectra.

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Section: Predicted Fe III Fluxesmentioning

confidence: 62%

“…Fe ii-strong quasars (Boroson & Green 1992;Kwan et al 1995). The Fe i atomic model consisted of 77 fine-structure levels (see Fig.…”

Section: Fe Imentioning

confidence: 99%

Theoretical Fei–iiiEmission‐Line Strengths from Active Galactic Nuclei with Broad‐Line Regions

Sigut

Pradhan

Nahar

2004

ApJ

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“…Models in which observed line width is based on orientation have recently been supported by evidence for a correlation between the ratio of the radio power and the monochromatic optical luminosity (an indication of the orientation angle) and the width of the Hb lines (Wills & Brotherton 1995). It has been postulated that the Fe II emission may arise in the accretion disk (Collin-Sou †rin, Hameury, & Joly 1988 ;Kwan et al 1995), so a face-on viewing angle would enhance the amount of Fe II observed.…”

Section: Models Based On Orientationmentioning

confidence: 97%

A Comprehensive Spectral and Variability Study of Narrow‐Line Seyfert 1 Galaxies Observed by ASCA . II. Spectral Analysis and Correlations

Leighly

1999

ASTROPHYS J SUPPL S

312

197

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I present a comprehensive and uniform analysis of 25 ASCA observations from 23 narrow-line Seyfert 1 galaxies (NLS1s). The spectral analysis and correlations are presented in this paper ; the reduction and time series analysis are presented in the companion paper. A maximum likelihood analysis conÐrms that the hard X-ray photon index is signiÐcantly steeper at more than 90% conÐdence in this sample of NLS1s compared with a random sample of Seyfert galaxies with broad optical lines. Soft excess emission was detected in 17 of the 19 objects that had no signiÐcant absorption, a result that demonstrates that soft excesses appear considerably more frequently in NLS1s than in Seyfert 1 galaxies with broad optical lines. The strength of the soft excess, parameterized using a Ñux ratio obtained from the blackbody plus power-law model, has a wide range of values in these objects (a factor of 50). The photon index was found to be correlated with the Hb FWHM, despite the small range of the latter parameter ; however, neither parameter is correlated with the strength of the soft excess or ROSAT slope. Therefore, assuming that an excess of soft photons causes the steep photon index and narrow Hb FWHM, that excess may lie primarily in the unobservable EUV. The strength of the soft excess is correlated with the variability parameters, so that objects with strong soft excesses show higher amplitude variability ; this potentially important result is not easily explained. While a range of 2 orders of magnitude in luminosity is represented, the temperature of the soft excess is approximately consistent throughout the sample, in contrast with expectations of simple accretion disk models. The presence of ionized absorption was sought using a two-edge model. It was found that this component appears to be typically less common in NLS1s and some evidence was found that the typical ionization state is lower compared with broad-line Seyfert galaxies. This fact, plus evidence for a correlation between the presence of the warm absorber and signiÐcant optical polarization, may imply that the inner warm absorber is missing or is too highly ionized to be detected, and only the outer, dusty, less ionized warm absorber is present in many cases. The iron line equivalent width appears to be similar among narrow and broad-line Seyfert galaxies. This could mean that reprocessing occurs with similar geometry in both classes of objects ; however, the detection of ionized iron lines in a few objects, implying possibly altered Ñuorescence yields, and poor statistics, makes this conclusion tentative. Constraints on physical processes and models based on extreme values of orientation and accretion rate for NLS1s are examined in light of the observational results.

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“…The Fe II emission in most AGNs is too strong to be explained by photoionization (Phillips 1978b;Kwan et al 1995); Fe II lines, and the other LILs as well, are more likely to be explained in the framework of collisional models where both the excitation of the lines and the ionization of the elements are due to collisions in a high density optically-thick medium illuminated mainly by hard X-rays; the Fe II emission region has a high density (10 10 < N e < 10 11 or 10 12 cm −3 ), a high column density (N H > 10 24 cm −2 ) and a low temperature (7500 < T < 10 000 K) (Collin-Souffrin et al 1980;1988b;Joly 1981;Clavel et al 1983;Collin-Souffrin & Lasota 1988;Kwan et al 1995). There is a significant correlation between Si III]/C III] and R 4570 ; Si III and C III have similar ionization potentials, but Si III] has a critical density more than one order of magnitude larger than C III] (1.1 × 10 11 and 5 × 10 9 cm −3 respectively); Si III]/C III] is thus a density indicator and becomes larger when density is higher; Si III]/C III] increases with increasing N e up to N e = 10 11 cm −3 (Aoki & Yoshida 1999;Wills et al 1999;Kuraszkiewicz et al 2000).…”

Section: High-and Low-ionization Linesmentioning

confidence: 99%

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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Fe II and Fe i Emission in IRAS 07598+6508 and PHL 1092

Cited by 28 publications

References 15 publications

Theoretical Fei–iiiEmission‐Line Strengths from Active Galactic Nuclei with Broad‐Line Regions

Theoretical Fei–iiiEmission‐Line Strengths from Active Galactic Nuclei with Broad‐Line Regions

A Comprehensive Spectral and Variability Study of Narrow‐Line Seyfert 1 Galaxies Observed by ASCA . II. Spectral Analysis and Correlations

A spectrophotometric atlas of Narrow-Line Seyfert 1 galaxies

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