Optical and near-UV spectroscopic properties of low-redshift jetted quasars in the main sequence context

Abstract

This paper presents new optical and near-UV spectra of 11 extremely powerful jetted quasars, with radio to optical flux density ratio > 103, that concomitantly cover the low-ionization emission of Mg iiλ2800 and h β as well as the Fe ii blends in the redshift range 0.35 ≲ z ≲ 1. We aim to quantify broad emission line differences between radio-loud (RL) and radio-quiet (RQ) quasars by using the 4D eigenvector 1 parameter space and its Main Sequence (MS) and to check the effect of powerful radio ejection on the low ionization broad emission lines. The h β and Mg iiλ2800 emission lines were measured by using non-linear multicomponent fittings as well as by analysing their full profile. We found that broad emission lines show large redward asymmetry both in h β and Mg iiλ2800. The location of our RL sources in a UV plane looks similar to the optical one, with weak Fe iiUV emission and broad Mg iiλ2800. We supplement the 11 sources with large samples from previous work to gain some general inferences. We found that, compared to RQ, our extreme RL quasars show larger median h β full width at half maximum (FWHM), weaker Fe ii emission, larger MBH, lower Lbol/LEdd, and a restricted bf space occupation in the optical and UV MS planes. The differences are more elusive when the comparison is carried out by restricting the RQ population to the region of the MS occupied by RL sources, albeit an unbiased comparison matching MBH and Lbol/LEdd suggests that the most powerful RL quasars show the highest redward asymmetries in h β.

Joint Analysis of the Iron Emission in the Optical and Near-Infrared Spectrum of I Zw 1

“…[47] shows a strong correlation between the optical FeII emission within the spectral range of 4434-4684 Å(centered at the wavelength 4570 Å), the peak intensity of [OIII]λ5007 oxygen emission line and the full width at half maximum (FWHM) of the broad component of the Balmer Hβ hydrogen emission profile. This led to the well-defined FWHM(Hβ) versus R FeII connection (R FeII generally denotes the ratio of the integrated FeII emission within 4434-4684 Å to the broad Hβ emission), that is, the well-known optical plane of the quasar main sequence [4,24,26,[55][56][57][58]. Within this framework, FeII emission not only plays a crucial role in discerning the underlying factors driving EV1 [4] but also serves as a link between line strength and the emitting gas physics for a diverse population of Type-1 AGNs along the EV1 plane.…”