The variability of UV/optical Fe ii emission lines in a QSO: SDSS J142052.43+525622.4

Zhao, Bi-Xuan; Bian, Wei-Hao; Yu, Lam H.; Wang, Chan

doi:10.1007/s10509-020-3733-7

“…Fe II emissions shown in the optical and ultraviolet (UV) spectra are prominent features in most active galactic nuclei (AGN; e.g., Boroson & Green 1992;Hu et al 2008;Shen & Ho 2014;Zhao et al 2020). With the principal component analysis of a low-z sample of 87 PalomarGreen quasars, Boroson & Green (1992) found that principal component 1 (PC1) is related to the relative strength of optical Fe II to the broad Hβ (R Fe , the ratio between the strength of Fe II emission within 4434-4684 Å and the broad Hβ), the FWHM of the broad Hβ (FWHM Hβ ), [O III]5007 strength, and that principal component 2 (PC2) links optical luminosity and α ox (optical-X-ray spectral index).…”

Section: Introductionmentioning

confidence: 99%

The Relation between the Optical Fe ii Emission and the Dimensionless Accretion Rate for Active Galactic Nuclei

Liu

¹

,

Bian

²

2022

ApJ

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It was suggested that the prominent feature of the optical Fe ii emission has a connection with the accretion process in active galactic nuclei (AGN). For a large sample of 4037 quasars (z < 0.8) with measured H β line dispersion (σ Hβ ) selected from the Sloan Digital Sky Survey (SDSS) and 120 compiled reverberation-mapped (RM) AGN, we use σ Hβ and the extended R BLR(Hβ)−L 5100 relation to calculate supermassive black holes masses (M BH) from the single-epoch spectra for the SDSS subsample, and σ Hβ from the mean spectra for the RM subsample. We find a strong correlation between the relative optical Fe ii strength R Fe and the dimensionless accretion rate M ̇ for the SDSS subsample with the Spearman correlation coefficient r s of 0.727, which is consistent with that derived from the mean spectra for the RM subsample. The magnitude of velocity shift of the optical Fe ii emission has a strong anticorrelation with M ̇ , whenever there is inflow or outflow. These strong correlations show that the optical Fe ii emission has an intimate connection with the accretion process. Assuming that the difference of M BH is due to the variable virial factor f for adopting FWHM H β as the velocity tracer, we find that there is a relation between f and FWHM H β , log f = − ( 0.41 ± 0.002 ) logFWHM H β + ( 1.719 ± 0.009 ) for the single-epoch spectrum. The relation between log f and σ Hβ is not too strong, suggesting that σ Hβ does not seem to depend much on the broad-line region inclination and a constant σ-based f is suitable for σ Hβ as the velocity tracer.

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UV FeII emission model of HE 0413−4031 and its relation to broad-line time delays

Zajaček,

Panda,

Pandey

et al. 2024

A&A

4

1

0

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FeII emission is a well-known contributor to the UV spectra of active galactic nuclei and the modeling of this part may affect the results obtained for the Mg II $ emission, which is one of the lines used for black hole mass measurements and cosmological applications. We tested different FeII emission models when modeling the UV emission of the intermediate-redshift quasar HE 0413-4031 to see how the use of a specific template affects the Mg II $ line properties and the measurement of the Mg II $ and UV Fe II time delays with respect to the continuum. We used the 11-year monitoring of the selected quasar HE 0413-4031 with the South African Large Telescope (SALT), and we supplemented this monitoring with the near-IR spectrum taken with the SOAR telescope, which gave access to the Hbeta $ and OIII 4959,5007$ emission lines at the rest frame and allowed for a precise measurement of the redshift. A new redshift determination ($z=1.39117 0.00017$) using OIII 4959,5007$ gave a very different value than the previous determination based only on the UV FeII pseudocontinuum ($z=1.3764$). It favors a different decomposition of the spectrum into MgII and UV FeII emissions. The line characteristics and the time delay of the MgII emission $ days) are not significantly affected. However, in comparison with the previous analysis, the rest-frame UV FeII time delay ($251^ km/s $ that is only slightly smaller than the MgII line FWHM. Hence the FeII-emitting material is more distant than the MgII-emitting gas in HE 0413-4031 by $ 0.023$ pc (4700 AU). The inferred velocity shift of both MgII and UV FeII lines with respect to the systemic redshift is now rather low, below 300 km $. In addition, we constructed an updated MgII radius-luminosity ($R-L$) relation from 194 sources, which is more than double the previous sample. The MgII $R-L$ relation is flatter than the UV FeII, optical FeII, and Hbeta $R-L$ relations. While the new decomposition of the spectrum is satisfactory, we see a need to create better FeII templates using the newest version of the code CLOUDY

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The variability of the broad-line Balmer decrement for quasars from the Sloan Digital Sky Survey reverberation mapping

Ma

¹

,

Li

²

,

Gu

³

et al. 2023

Monthly Notices of the Royal Astronomical Society

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Based on the spectral decomposition through a code of PrepSpec, the light curves (spanning 6.5 years in the observed frame) of the broad-line Balmer decrement, i.e., the flux ratio of the broad Hα to the broad Hβ line, are calculated for a sample of 44 Sloan Digital Sky Survey reverberation-mapped quasars (z < 0.53). It is found that the logarithm of the mean broad-line Balmer decrement is 0.62 with a standard deviation of 0.15 dex. The relations between the mean Balmer decrement and the SMBH accretion properties (the luminosity, black hole mass, Eddington ratio, accretion rate) are investigated and no obvious correlations are found. It is found that there are 27 quasars ($61\%$) showing strong negative correlations between the Balmer decrement variance and the continuum variance, i.e., the Balmer decrement would be smaller with larger continuum flux. Assuming that the dust obscuration leads to the variance in the Balmer decrement and the continuum, an expected slope is −1/3, which is not consistent with most of measured slopes. Using the interpolated cross-correlation function, the time delays between the inverse Balmer decrement and the continuum are measured for 14 quasars with the maximum correlation coefficient larger the 0.6. It suggests that the size corresponding to the Balmer decrement lag extends from the BLR size to the torus size.

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The variability of UV/optical Fe ii emission lines in a QSO: SDSS J142052.43+525622.4

Cited by 3 publications

References 46 publications

The Relation between the Optical Fe ii Emission and the Dimensionless Accretion Rate for Active Galactic Nuclei

The Relation between the Optical Fe ii Emission and the Dimensionless Accretion Rate for Active Galactic Nuclei

UV FeII emission model of HE 0413−4031 and its relation to broad-line time delays

The variability of the broad-line Balmer decrement for quasars from the Sloan Digital Sky Survey reverberation mapping

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