Infrared Spectroscopy of 15 Radio Galaxies at [FORMULA][F]2&lt;z&lt;2.6[/F][/FORMULA]

Iwamuro, Fumihide; Motohara, Kentaro; Maihara, Toshinori; Kimura, Masahiko; Eto, Shigeru; Shima, T.; Mochida, Daisaku; Wada, S.; Imai, Shiro; Aoki, Kentaro

doi:10.1086/378845

Cited by 30 publications

(54 citation statements)

References 35 publications

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“…10c). The "low-density and sub-solar metallicity" scenario appears to be consistent with the results reported by Iwamuro et al (2003), while the "high-density with wide metallicity distribution" scenario appears in agreement with the results reported by De Breuck et al (2000). Although some observational data with lower Civλ1549/Heiiλ1640 and Ciii]λ1909/Civλ1549 ratios appear to deviate from the model predictions with n H = 10 5 cm −3 (Fig.…”

Section: Gas Density and Metallicitysupporting

confidence: 89%

“…Since the broad emission lines and the strong ionizing continuum are blocked by this "natural coronagraph", we can investigate narrow UV emission lines whose spatial extension is roughly comparable to that of the host galaxies (∼10 2−4 pc), without any complex deblending of broad and narrow components for the emission lines. Although narrow emission lines of HzRGs are often strongly influenced by a radio jet in terms of kinematics and morphological properties (e.g., McCarthy et al 1991; Article published by EDP Sciences and available at http://www.edpsciences.org/aa or http://dx.doi.org/10.1051/0004-6361:20054127 Baum & McCarthy 2000), the ionization mechanism is mostly dominated by photoionization, not by shock ionization (e.g., Villar-Martin et al 1997;Allen et al 1998;Iwamuro et al 2003). Therefore, we can obtain information on the gas metallicity of the narrow-line regions (NLRs) by comparing the observed emission-line flux ratios with the predictions of photoionization models.…”

Section: Introductionmentioning

confidence: 99%

“…However, since the Nvλ1240 emission becomes very weak for metal-poor gas (i.e., Z gas < ∼ 1 Z ), only upper-limit fluxes on Nvλ1240 are available for the majority of the HzRG sample in De Breuck et al (2000), which makes the investigation of the metallicity evolution difficult. An additional issue is that Iwamuro et al (2003), based on rest-frame optical spectra obtained by sensitive near-infrared spectroscopy, recently reported that HzRGs at 2.0 < z < 2.6 tend to show sub-solar metallicities (Z gas ∼ 0.2 Z ), significantly lower than values reported by De Breuck et al (2000). Although it is clear that improved and additional observational data for a larger sample of HzRGs are required to reconcile this disagreement, both more sensitive measurements of Nvλ1240 and deeper near-infrared spectroscopic data are very difficult to obtain for HzRGs and QSO2s.…”

Section: Introductionmentioning

confidence: 99%

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Gas metallicity in the narrow-line regions of high-redshift active galactic nuclei

Nagao

Maiolino

Marconi

2006

A&A

142

216

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We analyze optical (UV rest-frame) spectra of X-ray selected narrow-line QSOs at redshift 1.5 < ∼ z < ∼ 3.7 found in the Chandra Deep Field South and of narrow-line radio galaxies at redshift 1.2 < ∼ z < ∼ 3.8 to investigate the gas metallicity of the narrow-line regions and their evolution in this redshift range. Such spectra are also compared with UV spectra of local Seyfert 2 galaxies. The observational data are inconsistent with the predictions of shock models, suggesting that the narrow-line regions are mainly photoionized. The photoionization models with dust grains predict line flux ratios which are also in disagreement with most of the observed values, suggesting that the high-ionization part of the narrowline regions (which is sampled by the available spectra) is dust-free. The photoionization dust-free models provide two possible scenarios which are consistent with the observed data: low-density gas clouds (n H < ∼ 10 3 cm −3 ) with a sub-solar metallicity (0.2 < ∼ Z gas /Z < ∼ 1.0), or high-density gas clouds (n H ∼ 10 5 cm −3 ) with a wide range of gas metallicity (0.2 < ∼ Z gas /Z < ∼ 5.0). Regardless of the specific interpretation, the observational data do not show any evidence for a significant evolution of the gas metallicity in the narrow-line regions within the redshift range 1.2 < ∼ z < ∼ 3.8. Instead, we find a trend for more luminous active galactic nuclei to have more metal-rich gas clouds (luminosity-metallicity relation), which is in agreement with the same finding in the studies of the broad-line regions. The lack of evolution for the gas metallicity of the narrow-line regions implies that the major epoch of star formation in the host galaxies of these active galactic nuclei is at z > ∼ 4.

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Section: Gas Density and Metallicitysupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Gas metallicity in the narrow-line regions of high-redshift active galactic nuclei

Nagao

Maiolino

Marconi

2006

A&A

142

216

View full text Add to dashboard Cite

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“…Many attempts have been made during last several decades to measure Fe ii (UV)/Mg ii ratios in QSOs and connect them with corresponding abundances (e.g., Kwan & Krolik 1981;Iwamuro et al 2002Iwamuro et al , 2003Iwamuro et al , 2004Freudling et al 2003). Two major techniques for subtracting or estimating the Fe ii emission spectra exist.…”

Section: Introductionmentioning

confidence: 99%

Modeling FeiiEmission and Revised Feii(UV) Empirical Templates for the Seyfert 1 Galaxy I Zw 1

Bruhweiler

Verner

2008

ApJ

118

173

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We use the narrow-lined broad-line region ( BLR) of the Seyfert 1 galaxy, I Zw 1, as a laboratory for modeling the ultraviolet (UV ) Fe ii 2100Y3050 8 emission complex. We calculate a grid of Fe ii emission spectra representative of BLR clouds and compare them with the observed I Zw 1 spectrum. Our predicted spectrum for log n H /(cm À3 ) ½ ¼ 11:0, log È H /(cm À2 s À1 ) ½ ¼ 20:5, and /(1 km s À1 ) ¼ 20, using Cloudy and an 830 level model atom for Fe ii with energies up to 14.06 eV, gives a better fit to the UV Fe ii emission than models with fewer levels. Our analysis indicates (1) the observed UV Fe ii emission must be corrected for an underlying Fe ii pseudocontinuum; (2) Fe ii emission peaks can be misidentified as that of other ions in active galactic nuclei (AGNs) with narrow-lined BLRs possibly affecting deduced physical parameters; (3) the shape of 4200Y4700 8 Fe ii emission in I Zw 1 and other AGNs is a relative indicator of narrow-line region ( NLR) and BLR Fe ii emission; (4) predicted ratios of Ly , C iii], and Fe ii emission relative to Mg ii k2800 agree with extinction corrected observed I Zw 1 fluxes, except for C iv k1549; (5) the sensitivity of Fe ii emission strength to microturbulence casts doubt on existing relative Fe/ Mg abundances derived from Fe ii (UV)/Mg ii flux ratios. Our calculated Fe ii emission spectra, suitable for BLRs in AGNs, are available at

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“…in type 2 AGNs. However, in high redshift objects (mostly radio-galaxies and type 2 QSOs) there are often only a few, faint narrow lines detected that can be used to constrain the NLR metallicity [17,18,19,20]. As a consequence of the faintness of the narrow lines, the sample of high-z objects for which the NLR metallicity has been investigated is much smaller (∼60 objects) than the broad line sample, and currently limited to z<4.…”

Section: Metallicity In the Nlr Of High-z Agnsmentioning

confidence: 99%

Early metal enrichment in high-redshift quasars

Maiolino¹,

Giobbi²,

Tornambé³

et al. 2009

AIP Conference Proceedings

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Abstract. Quasars are powerful systems whose spectrum is rich of metal features that allow us to investigate the chemical evolution of galaxies at very high redshift, even close to the reionization epoch. I review the main observational constraints on the metallicity of quasars host galaxies at high redshift and discuss the implications and issues for models of galaxy evolution in the early universe.

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Infrared Spectroscopy of 15 Radio Galaxies at [FORMULA][F]2<z<2.6[/F][/FORMULA]

Cited by 30 publications

References 35 publications

Gas metallicity in the narrow-line regions of high-redshift active galactic nuclei

Gas metallicity in the narrow-line regions of high-redshift active galactic nuclei

Modeling FeiiEmission and Revised Feii(UV) Empirical Templates for the Seyfert 1 Galaxy I Zw 1

Early metal enrichment in high-redshift quasars

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