Metal Content in Relativistically Jetted and Radio-Quiet Quasars in the Main Sequence Context

Abstract

The optical and UV properties of radio-quiet (RQ) and radio-loud (RL, relativistically “jetted”) active galactic nuclei (AGN) are known to differ markedly; however, it is still unclear what is due to a sample selection and what is associated with intrinsic differences in the inner workings of their emitting regions. Chemical composition is an important parameter related to the trends of the quasar main sequence. Recent works suggest that in addition to physical properties such as density, column density, and ionization level, strong Feii emitters require very high metal content. Little is known, however, about the chemical composition of jetted radio-loud sources. In this short note, we present a pilot analysis of the chemical composition of low-z radio-loud and radio-quiet quasars. Optical and UV spectra from ground and space were combined to allow for precise measurements of metallicity-sensitive diagnostic ratios. The comparison between radio-quiet and radio-loud was carried out for sources in the same domain of the Eigenvector 1/main sequence parameter space. Arrays of dedicated photo-ionization simulations with the input of appropriate spectral energy distributions indicate that metallicity is sub-solar for RL AGN, and slightly sub-solar or around solar for RQ AGN. The metal content of the broad line-emitting region likely reflects a similar enrichment story for both classes of AGN not involving recent circum-nuclear or nuclear starbursts.

Accretion/Ejection Phenomena and Emission-Line Profile (A)symmetries in Type-1 Active Galactic Nuclei

“…A second assumption is the relatively constant physical conditions within the BLR. This is likely the case if the restriction is made to objects belonging to Population B (i.e., showing a prominent redward asymmetry in the Balmer lines) in the innermost part of their emitting regions, the so-called very broad line region (e.g., [103,104]): for the VBLR, the ionization parameter has been estimated as high as log U ∼ −0.5-0, with a moderate density logn H ∼ 10 (cm −3 ) [5,105], with solar or somewhat subsolar metallicity [105]. These physical conditions have been derived since the late 1970s [106]-before the realization that a large fraction of type-1 AGN emit substantial FeII-and are appropriate for sources that are weak FeII emitters.…”

“…Larger shifts occur if a ≈ 0.533 0.5 [95]. Because log U ∼ −0.5-0 for the VBLR gas of Population B AGN [5,105], there is a good agreement between the amplitude of the redshift and the ionization parameter value at the innermost edge of the BLR.…”

Broad-line region in active galactic nuclei: Dusty or dustless?

“…If f c is instead on the order of 0.2-0.3 (EW requested from the model is then ∼300 to 400 Å), there is a large parameter region with n H ∼ 10 11 −10 12 cm −3 and Φ H ∼ 3 × 10 17 cm −2 s −1 that can give such a line intensity (lower density favoured for higher covering factor). The high density requested for the LIL region is not surprising, as many recent works have obtained such values on the basis of modelling line properties (Bruhweiler & Verner 2008;Panda et al 2018Panda et al , 2019bPanda et al , 2020Panda 2021bPanda , 2022Marziani et al 2021Marziani et al , 2023Śniegowska et al 2021;Garnica et al 2022) or just by theoretical argument of radiation pressure confinement (Baskin & Laor 2018). Whether the region is dusty or dustless, the values of Φ H should be smaller than 10 19 cm −2 s −1 for the density 10 12 cm −3 and smaller than 6 × 10 19 cm −2 s −1 for an unlikely high cloud density 10 14 cm −3 in order to match the observed EW of Hβ line.…”

Spectral Variability Studies in Active Galactic Nuclei: Exploring Continuum and Emission Line Regions in the Age of LSST and JWST

“…Stars were cataloged into seven principal spectral types (OBAFGKM) in the HR Diagram. Population A sources included local Narrow-Line Seyfert 1 galaxies (NLS1s) as well as more massive, highly accreting objects that are predominantly classified as radio-quiet or non-jetted sources, e.g., [29,80,81]. These sources demonstrate FWHM(Hβ) estimates of ≤4000 km s −1 .…”