The Fe II problem in NLS1s

Collin, S.; Joly, M.

doi:10.1016/s1387-6473(00)00093-2

Cited by 71 publications

(72 citation statements)

References 35 publications

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“…We have also to consider that, even if 4DE1 eases the systematization of quasar spectral properties, a full understanding of some parameters used in the formulation of the 4DE1 itself is still missing. For example, the emission mechanism of Feii is still unclear, especially for strong Feii emitters as found in A3 and A4 spectral types ( [21,44,58] review of the "Feii problem").…”

Section: The 4de1 Main Sequencementioning

confidence: 99%

Low- and High-zHighly Accreting Quasars in the 4D Eigenvector 1 Context

Marziani¹,

Sulentic²,

Negrete³

et al. 2014

Astronomical Review

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Highly accreting quasars are characterized by distinguishing properties in the 4D eigenvector 1 parameter space that make them easily recognizable over a broad range range of redshift and luminosity. The 4D eigenvector 1 approach allows us to define selection criteria that go beyond the restriction to Narrow Line Seyfert 1s identified at low redshift. These criteria are probably able to isolate sources with a defined physical structure i.e., a geometrically thick, optically thick advectiondominated accretion disk (a "slim" disk). We stress that the importance of highly accreting quasars goes beyond the understanding of the details of their physics: their Eddington ratio is expected to saturate toward values of order unity, making them possible cosmological probes.

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Section: The 4de1 Main Sequencementioning

confidence: 99%

Low- and High-zHighly Accreting Quasars in the 4D Eigenvector 1 Context

Marziani¹,

Sulentic²,

Negrete³

et al. 2014

Astronomical Review

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“…In analogy to high-z quasars they may have super-solar metal abundances, as indicated by a number of observations: An overabundance of iron was suggested to explain the strong optical FeII emission in NLSy1s (Collin & Joly 2000). Supersolar Fe or Ne provide a possible explanation for the peculiar absorption features around ∼1 keV seen in some NLSy1 galaxies (e.g., Ulrich et al 1999;Turner et al 1999).…”

Section: Evidence For Supersolar Metallicity In Nlsy1 Galaxiesmentioning

confidence: 99%

Research NoteSupersolar metal abundances and the Broad Line Region of Narrow-line Seyfert 1 galaxies

Komossa

Mathur

2001

A&A

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Abstract. Narrow-line Seyfert 1 galaxies (NLSy1) are intriguing due to their extreme continuum and emission line properties which are not yet well understood. This paper is motivated by the recent suggestion that NLSy1 galaxies might be young active galactic nuclei (AGNs) and that they may have supersolar metal abundances. We have examined the stability of broad emission line region (BLR) clouds under isobaric perturbation and its dependence on gas metal abundances. We show that supersolar metallicity increases the range where multiple phases in pressure balance may exist. This is particularly important for NLSy1s with steep X-ray spectra where it delays the trend of hindrance of a multi-phase equilibrium. Finally, the role of warm absorbers in the context of this scenario is assessed.

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“…Calculating the Fe ii emission spectrum is much more difficult, and the influence of unknown parameters such as internal turbulence velocities, emission-line transport, pumping by the incident continua, line fluorescence, and metallicity, which affect the emergent Fe ii spectrum, is still not well understood (e.g., WNW85; Netzer et al 1985;Joly 1987;Bautista & Pradhan 1998;Sigut & Pradhan 1998;Verner et al 1999Verner et al , 2003Collin & Joly 2000). In spite of these uncertainties it has been shown that the Fe ii emission strength of Seyfert 1 galaxies and quasars can be measured using empirically derived Fe ii emission template spectra (WNW85; Laor et al 1997;McIntosh et al 1999;Dietrich et al 2002a;Iwamuro et al 2002).…”

Section: Fe II Emissionmentioning

confidence: 99%

“…Given the complexity of the Fe ii emission spectrum, accurate iron abundances are not yet straightforward to deduce and a full synthesis of individual quasar spectra is required. This seriously complicates such measurements because the Fe ii emission is hard to synthesize (e.g., Verner et al 1999Verner et al , 2003Collin & Joly 2000;Sigut & Pradhan 1998, 2003.…”

Section: Introductionmentioning

confidence: 99%

Feii/MgiiEmission‐Line Ratio in High‐Redshift Quasars

Dietrich

Hamann

Appenzeller³

et al. 2003

ApJ

128

146

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We present results of the analysis of near-infrared spectroscopic observations of six high-redshift quasars (ze4), emphasizing the measurement of the ultraviolet Fe ii/Mg ii emission-line strength to estimate the beginning of intense star formation in the early universe. To investigate the evolution of the Fe ii/Mg ii ratio over a wider range in cosmic time, we measured this ratio for composite quasar spectra that cover a redshift range 0dzd5 with nearly constant luminosity, as well as for those that span $6 orders of magnitude in luminosity. A detailed comparison of the high-redshift quasar spectra with those of low-redshift quasars with comparable luminosity shows essentially the same Fe ii/Mg ii emission ratios and very similar continuum and line spectral properties, i.e., a lack of evolution of the relative iron-to-magnesium abundance of the gas in bright quasars since z ' 5. Current nucleosynthesis and stellar evolution models predict that -elements such as magnesium are produced in massive stars ending in Type II supernovae, while iron is formed predominantly in Type Ia supernovae with intermediate-mass progenitors. This results in an iron enrichment delay of $0.2-0.6 Gyr. We conclude that intense star formation activity in the host galaxies of ze4 quasars must have started already at an epoch corresponding to z f ' 6-9, when the age of the universe was $0.5 Gyr (H 0 ¼ 72 km s À1 Mpc À1 , M ¼ 0:3, Ã ¼ 0:7). This epoch corresponds well to the reionization era of the universe.

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The Fe II problem in NLS1s

Cited by 71 publications

References 35 publications

Low- and High-zHighly Accreting Quasars in the 4D Eigenvector 1 Context

Low- and High-zHighly Accreting Quasars in the 4D Eigenvector 1 Context

Research NoteSupersolar metal abundances and the Broad Line Region of Narrow-line Seyfert 1 galaxies

Feii/MgiiEmission‐Line Ratio in High‐Redshift Quasars

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