We review the properties of the established Scaling Relations (SRs) of galaxies and active
galactic nuclei (AGN), focusing on their origin and expected evolution back in time, providing …

The Eigenvector 1 schema, or the main sequence of quasars, was introduced as an
analogous scheme to the HR diagram that would allow us to understand the more complex …

We present an analysis of UV spectra of 13 quasars believed to belong to extreme
Population A (xA) quasars, aimed at the estimation of the chemical abundances of the broad …

Context. Dust in active galactic nuclei is clearly present right outside the broad-line region
(BLR) in the form of a dusty molecular torus. However, some models of the BLR predict that …

Context. The 4D Eigenvector 1 empirical formalism (4DE1) and its main sequence (MS) for
quasars has emerged as a powerful tool for organising the diversity among quasar …

The study of the broad-line region (BLR) using reverberation mapping has allowed us to
establish an empirical relation between the size of this line-emitting region and the …

Context. We test the scenario according to which the broad absorption line (BAL)
phenomenon in quasars (QSOs) is not a temporary stage of their life. In this scenario, the …

Context. We present an analysis of UV spectra of quasars at intermediate redshifts believed
to belong to the extreme Population A (xA), aimed to estimate the chemical abundances of …

The dynamics of the broad line region (BLR) in active galaxies is an open question; direct
observational constraints suggest a predominantly Keplerian motion, with possible traces of …

Aims. Modelling the low-ionisation lines (LILs) in active galactic nuclei (AGNs) still faces
problems in explaining the observed equivalent widths (EWs) when realistic covering factors …