An Observational Link between AGN Eddington Ratio and [N ii]λ6583/Hα at 0.6 &lt; z &lt; 1.7

Oh, Kyuseok; Ueda, Yoshihiro; Akiyama, Masayuki; Suh, Hyewon; Koss, Michael; Kashino, Daichi; Hasinger, G.

doi:10.3847/1538-4357/ab288b

Cited by 8 publications

(7 citation statements)

References 96 publications

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“…These results are more in agreement with those found by Oh et al (2017) who compared [N ]𝜆6583/H𝛼, which is sensitive to O/H abundances, with 𝜆 Edd for a sub-sample of the local hard X-ray-selected BAT AGNs (297 sources at 0.01 < 𝑧 < 0.40) as well as at redshift beyond the local Universe (e.g. 53 sources at 0.6 < 𝑧 < 1.7; Oh et al 2019) and found a clear anti-correlation between those two quantities. Moreover, Matsuoka et al (2011) used optical spectra of high redshift (2.3 < 𝑧 < 3.0) quasars and compared different metallicity sensitive emission line ratios with 𝜆 Edd .…”

Section: Metallicity and Accretion Ratesupporting

confidence: 90%

Oxygen abundances in the narrow line regions of Seyfert galaxies and the metallicity-luminosity relation

Armah¹,

Dors²,

Oh³

et al. 2023

Preprint

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We present oxygen abundances relative to hydrogen (O/H) in the narrow line regions (NLRs) gas phases of Seyferts 1 (Sy 1s) and Seyferts 2 (Sy 2s) Active Galactic Nuclei (AGNs). We used fluxes of the optical narrow emission line intensities [3 500 < 𝜆(Å) < 7 000] of 561 Seyfert nuclei in the local universe (𝑧 0.31) from the second catalog and data release (DR2) of the BAT AGN Spectroscopic Survey, which focuses on the Swift-BAT hard X-ray ( 10 keV) detected AGNs. We derived O/H from relative intensities of the emission lines via the strong-line methods. We find that the AGN O/H abundances are related to their hosts stellar masses and that they follow a downward redshift evolution. The derived O/H together with the hard X-ray luminosity (𝐿 X ) were used to study the X-ray luminosity-metallicity (𝐿 X -𝑍 NLR ) relation for the first time in Seyfert galaxies. In contrast to the broad-line focused (𝐿 X -𝑍 BLR ) studies, we find that the 𝐿 X -𝑍 NLR exhibit significant anti-correlations with the Eddington ratio (𝜆 Edd ) and these correlations vary with redshifts. This result indicates that the low-luminous AGNs are more actively undergoing Interstellar Medium (ISM) enrichment through star formation in comparison with the more luminous X-ray sources. Our results suggest that the AGN is somehow driving the galaxy chemical enrichment, as a result of the inflow of pristine gas that is diluting the metal rich gas, together with a recent cessation on the circumnuclear star-formation.

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Section: Metallicity and Accretion Ratesupporting

confidence: 90%

Oxygen abundances in the narrow line regions of Seyfert galaxies and the metallicity-luminosity relation

Armah¹,

Dors²,

Oh³

et al. 2023

Preprint

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“…In order to explain the complex observational features of the broad Balmer regions, we have fitted the optical spectra of BAT AGNs using multiple Gaussian components (Mullaney & Ward 2008;La Mura et al 2009;Suh et al 2015;Oh et al 2019;Suh et al 2020). Several previous studies have suggested a possible physical origin of complex broad lines (and/or double-peaked narrow emission lines), including rotating disks, a binary broad-line region in a binary supermassive black hole system, complex narrow-line region kinematics, and biconical outflows (Gaskell 1983;Chen & Halpern 1989;Zheng et al 1990;Eracleous & Halpern 1994;Eracleous et al 2009;Shen et al 2011); however, this remains an open question.…”

Section: Complex Emission-line Featuresmentioning

confidence: 99%

BASS. XXIV. The BASS DR2 Spectroscopic Line Measurements and AGN Demographics

Oh¹,

Koss²,

Ueda³

et al. 2022

ApJS

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We present the second catalog and data release of optical spectral line measurements and active galactic nucleus (AGN) demographics of the BAT AGN Spectroscopic Survey, which focuses on the Swift-BAT hard X-ray detected AGNs. We use spectra from dedicated campaigns and publicly available archives to investigate spectral properties of most of the AGNs listed in the 70 month Swift-BAT all-sky catalog; specifically, 743 of the 746 unbeamed and unlensed AGNs (99.6%). We find a good correspondence between the optical emission line widths and the hydrogen column density distributions using the X-ray spectra, with a clear dichotomy of AGN types for N H = 1022 cm−2. Based on optical emission-line diagnostics, we show that 48%–75% of BAT AGNs are classified as Seyfert, depending on the choice of emission lines used in the diagnostics. The fraction of objects with upper limits on line emission varies from 6% to 20%. Roughly 4% of the BAT AGNs have lines too weak to be placed on the most commonly used diagnostic diagram, [O iii]λ5007/Hβ versus [N ii]λ6584/Hα, despite the high signal-to-noise ratio of their spectra. This value increases to 35% in the [O iii]λ5007/[O ii]λ3727 diagram, owing to difficulties in line detection. Compared to optically selected narrow-line AGNs in the Sloan Digital Sky Survey, the BAT narrow-line AGNs have a higher rate of reddening/extinction, with Hα/Hβ > 5 (∼36%), indicating that hard X-ray selection more effectively detects obscured AGNs from the underlying AGN population. Finally, we present a subpopulation of AGNs that feature complex broad lines (34%, 250/743) or double-peaked narrow emission lines (2%, 17/743).

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“…To further investigate the correlation of [Si VI] λ1.9640 with X-ray emission, we consider the Eddington ratio (L bol /L Edd ) dependence (see Figure 18 top left). Previous studies by Oh et al (2017Oh et al ( , 2019 found a correlation between the Eddington ratio and narrow-line emission. The correlation is most likely caused by X-ray heating processes or removal of material by an energetic outflow.…”

Section: Comparison Of CL and X-ray Luminositiesmentioning

confidence: 71%

BASS. XXVIII. Near-infrared Data Release 2: High-ionization and Broad Lines in Active Galactic Nuclei*

Brok¹,

Koss²,

Trakhtenbrot³

et al. 2022

ApJS

Self Cite

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We present the BAT AGN Spectroscopic Survey (BASS) Near-infrared Data Release 2 (DR2), a study of 168 nearby ( z ¯ = 0.04 , z < 0.6) active galactic nuclei (AGN) from the all-sky Swift Burst Array Telescope X-ray survey observed with the Very Large Telescope (VLT)/X-shooter in the near-infrared (NIR; 0.8–2.4 μm). We find that 49/109 (45%) Seyfert 2 and 35/58 (60%) Seyfert 1 galaxies observed with VLT/X-shooter show at least one NIR high-ionization coronal line (CL; ionization potential χ > 100 eV). Comparing the emission of the [Si vi] λ1.9640 CL with the X-ray emission for the DR2 AGN, we find a significantly tighter correlation, with a lower scatter (0.37 dex) than that for the optical [O iii] λ5007 line (0.71 dex). We do not find any correlation between CL emission and the X-ray photon index Γ. We find a clear trend of line blueshifts with increasing ionization potential in several CLs, such as [Si vi] λ1.9640, [Si x] λ1.4300, [S viii] λ0.9915, and [S ix] λ1.2520, indicating the radial structure of the CL region. Finally, we find a strong underestimation bias in black hole mass measurements of Sy 1.9 using broad Hα due to the presence of significant dust obscuration. In contrast, the broad Paα and Paβ emission lines are in agreement with the M–σ relation. Based on the combined DR1 and DR2 X-shooter sample, the NIR BASS sample now comprises 266 AGN with rest-frame NIR spectroscopic observations, the largest set assembled to date.

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An Observational Link between AGN Eddington Ratio and [N ii]λ6583/Hα at 0.6 < z < 1.7

Cited by 8 publications

References 96 publications

Oxygen abundances in the narrow line regions of Seyfert galaxies and the metallicity-luminosity relation

Oxygen abundances in the narrow line regions of Seyfert galaxies and the metallicity-luminosity relation

BASS. XXIV. The BASS DR2 Spectroscopic Line Measurements and AGN Demographics

BASS. XXVIII. Near-infrared Data Release 2: High-ionization and Broad Lines in Active Galactic Nuclei*

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