Metallicity Evolution of AGNs

Nagao, Tohru; Maiolino, R.; Marconi, A.; Matsuoka, Kenta; Taniguchi, Yoshiaki

doi:10.1017/s1743921310005594

Cited by 3 publications

(4 citation statements)

References 32 publications

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“…At present, the better-defined correlation of the metal content appears to be with luminosity (Shin et al 2013). This correlation is especially strong, and is confirmed by diagnostics based on narrow lines (Nagao et al 2006a(Nagao et al , 2010. Dietrich et al (2009) found that the gas metallicity of the broad-line region is supersolar with 3 Z/Z in luminous, intermediate-redshift quasars, from measurements of the Niii]λ1750/Oiii]λ1663 and Nvλ1240/Civλ1549 emission line ratios.…”

Section: Possible Interpretation Of Lower Chemical Abundance At High Zmentioning

confidence: 73%

GTC spectra ofz≈ 2.3 quasars: comparison with local luminosity analogs

Sulentic¹,

Marziani²,

Olmo³

et al. 2014

A&A

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Context. The advent of 8−10 m class telescopes for the first time makes it possible to compare in detail quasars with similar luminosity and very different redshifts. Aims. We conducted a search for z-dependent gradients in line-emission diagnostics and derived physical properties by comparing, in a narrow bolometric luminosity range (log L ∼ 46.1± 0.4 [erg s −1 ]), some of the most luminous local z < 0.6 quasars with some of the lowest luminosity sources yet found at redshift z = 2.1−2.5. Methods. Moderate signal-to-noise ratio spectra for 22 high-redshift sources were obtained with the 10.4 m Gran Telescopio Canarias (GTC), for which the HST (largely the Faint Object Spectrograph) archive provides a low-redshift control sample. We compared the spectra in the context of the 4D Eigenvector 1 formalism, meaning that we divided both source samples into highly accreting population A and population B sources accreting at a lower rate. Results. Civλ1549, the strongest and most reliable diagnostic line, shows very similar properties at both redshifts, which confirms the Civλ1549 profile differences at high redshift between populations A and B, which are well established in local quasars. The Civλ1549 blueshift that appears quasi-ubiquitous in higher L sources is found in only half (population A) of the quasars observed in the two samples. A Civλ1549 evolutionary Baldwin effect is certainly disfavored. We find evidence for lower metallicity in the GTC sample that may point toward a gradient with z. No evidence for a gradient in M BH or L/L Edd is found. Conclusions. Spectroscopic differences established at low z are also present in much higher redshift quasars. Our results on the Civλ1549 blueshift suggest that it depends both on source luminosity and L/L Edd . Given that our samples involve sources with very similar luminosity, the evidence for a systematic metallicity decrease, if real, points toward an evolutionary effect. Our samples are not large enough to effectively constrain possible changes of M BH or L/L Edd with redshift. The two samples appear representative of a slowly evolving quasar population that is most likely present at all redshifts.

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Section: Possible Interpretation Of Lower Chemical Abundance At High Zmentioning

confidence: 73%

GTC spectra ofz≈ 2.3 quasars: comparison with local luminosity analogs

Sulentic¹,

Marziani²,

Olmo³

et al. 2014

A&A

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“…With this large sample and the composite spectra with high signal-to-noise ratio (S/N), we can get a precise measurement of line ratio to estimate the metallicity of quasar BLR and then get a better statistical investigation for the evolution of metallicity in a wide range of BH mass and bolometric luminosity. We mainly focus on the metallicity of BLR in this work instead of narrow line region (NLR) which is supposed to trace the spatial scale (Bennert et al 2006a,b) and the enrichment history of quasar host galaxies (Nagao et al 2010). This is because that some typical NLR metallicity indicators, like [N II]/Hα (Ludwig et al 2012;Du et al 2014), has lines that exceed the wavelength coverage of SDSS spectra, especially at higher redshift.…”

Section: Introductionmentioning

confidence: 99%

“…Due to this problem, it is not easy to do sufficient statistical analysis on NLR with a wide redshift range comparing to BLR. The metallicity in quasar BLR can be affected by local starbursts at the center of quasar host galaxies (Nagao et al 2010), so it may not well present the global metallicity in host galax-ies. But comparing the metallicity in the quasar BLR and its host galaxies can provide crucial information on the different history of star formation and metallicity enrichment in different parts of the galaxies.…”

Section: Introductionmentioning

confidence: 99%

The evolution of chemical abundance in quasar broad line region

Bian

Shen

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We study the relation between the metallicity of quasar broad line region (BLR) and black hole (BH) mass (10 7.5 M ⊙ ∼ 10 10 M ⊙ ) and quasar bolometric luminosity (10 44.6 erg/s ∼ 10 48 erg/s) using a sample of ∼130,000 quasars at 2.25 ≤ z ≤ 5.25 from Sloan Digital Sky Survey (SDSS) Data Release 12 (DR12). We generate composite spectra by stacking individual spectra in the same BH mass (bolometric luminosity) and redshift bins and then estimate the metallicity of quasar BLR using metallicitysensitive broad emission-line flux ratios based on the photoionization models. We find a significant correlation between quasar BLR metallicity and BH mass (bolometric luminosity) but no correlation between quasar BLR metallicity and redshift. We also compare the metallicity of quasar BLR and that of host galaxies inferred from the mass-metallicity relation of star-forming galaxy at z ∼ 2.3 and z ∼ 3.5. We find quasar BLR metallicity is 0.3 ∼ 1.0 dex higher than their host galaxies. This discrepancy cannot be interpreted by the uncertainty due to different metallicity diagnostic methods, mass-metallicity relation of galaxy, metallicity gradient in quasar host galaxies, BH mass estimation, the effect of different spectral energy distribution (SED) models, and a few other potential sources of uncertainties. We propose a possibility that the high metallicity in quasar BLR might be caused by metal enrichment from massive star formation in the nucleus region of quasars or even the accretion disk.

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“…under the assumption of constant density (n 9 is in units of 10 9 cm −3 ). The metallicity is scaled to 10Z , appropriate for highly accreting quasars detected at high redshift [36,41,47,48]. The corresponding outflow kinetic power, with outflow v in units of 5000 km s −1 , is:…”

Section: Feedback Effects Of Accreting Black Holesmentioning

confidence: 99%

Broad UV Emission Lines in Type-1 Active Galactic Nuclei: A Note on Spectral Diagnostics and the Excitation Mechanism

Marziani

Olmo

Perea

et al. 2020

Atoms

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This paper reviews several basic emission properties of the UV emission lines observed in the spectra of quasars and type-1 active galactic nuclei, mainly as a function of the ionization parameter, metallicity, and density of the emitting gas. The analysis exploits a general-purpose 4D array of the photoionization simulations computed using the code CLOUDY, covering ionization parameter in the range 10−4.5–10+1.0, hydrogen density nH∼107–1014 cm−3, metallicity Z between 0.01 and 100 Z⊙, and column density in the range 1021–1023 cm−2. The focus is on the most prominent UV emission lines observed in quasar spectra, namely Nvλ1240, Siivλ1397, Oiv]λ1402, Civλ1549, Heiiλ1640, Aliiiλ1860, Siiii]λ1892, and Ciii]λ1909, and on the physical conditions under which electron-ion impact excitation is predicted to be the dominant line producer. Photoionization simulations help constrain the physical interpretation and the domain of applicability of spectral diagnostics derived from measurements of emission line ratios, reputed to be important for estimating the ionization degree, density, and metallicity of the broad line emitting gas, as well as the relative intensity ratios of the doublet or multiplet components relevant for empirical spectral modeling.

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Metallicity Evolution of AGNs

Cited by 3 publications

References 32 publications

GTC spectra ofz≈ 2.3 quasars: comparison with local luminosity analogs

GTC spectra ofz≈ 2.3 quasars: comparison with local luminosity analogs

The evolution of chemical abundance in quasar broad line region

Broad UV Emission Lines in Type-1 Active Galactic Nuclei: A Note on Spectral Diagnostics and the Excitation Mechanism

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