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

Abstract

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

Virial Black Hole Masses for Active Galactic Nuclei behind the Magellanic Clouds

“…We also demonstrate the optical plane of the Eigenvector 1, or the quasar main sequence for the subsample (41/165) of our sources with reliable measurements of the FWHM(Hβ) and the strength of the optical Fe II emission, i.e., R Fe II . There is an overall agreement with the SDSS-based main-sequence diagram where we notice a discernible trend-increasing Eddington ratio with an increase/decrease in the R Fe II /FWHM(Hβ), along the main sequence as found in earlier works (Sun & Shen 2015;Marziani et al 2018;Panda et al 2019bPanda et al , 2020Zajaček et al 2024). The sources with R Fe II  1 will be especially interesting to follow up in the optical and near-infrared spectral regions to characterize their variable nature and evaluate the strength of other low-ionization lines, e.g., Ca II triplet (emitting at λλ8498, 8542, and 8662) and OI λ8446, which are efficient proxies to reveal the physical conditions of the low-ionization line-emitting region in such AGNs (Martínez-Aldama et al 2015;Marinello et al 2016Marinello et al , 2020Martínez-Aldama et al 2021a, 2021bPanda , 2021c.…”

Probing the C iv Continuum Size–Luminosity Relation in Active Galactic Nuclei with Photometric Reverberation Mapping

“…Recent studies have improved the R-L relation also in the Mg II region (z ∼ 0.004-1.89) expanding the sample size to 200 AGN(Cao et al 2024;Shen et al 2024;Zajaček et al 2024), although the presence of the Fe II pseudocontinuum underneath and around the Mg II emission line complicates the already complex kinematics for this region(Panda et al 2019a;Popović et al 2019;Zajaček et al 2024;Pandey et al 2024). …”