The last 25 years saw a major step forward in the analysis of optical and UV spectroscopic
data of large quasar samples. Multivariate statistical approaches have led to the definition of …

It is well known that reverberation mapping of active galactic nuclei (AGNs) reveals a
relationship between AGN luminosity and the size of the broad-line region, and that use of …

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 …

Winds accelerated by active galactic nuclei (AGNs) are invoked in the most successful
models of galaxy evolution to explain the observed physical and evolutionary properties of …

We address the effect of orientation of the accretion disk plane and the geometry of the
broad-line region (BLR) as part of an effort to understand the distribution of quasars in …

Quasars have been proposed as a new class of standard candles analogous to supernovae,
since their large redshift range and high luminosities make them excellent candidates. The …

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. The most highly accreting quasars are of special interest in studies of the physics of
active galactic nuclei (AGNs) and host galaxy evolution. Quasars accreting at high rates (L/L …

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 …

We report on the variability of a multi-component broad absorption line (BAL) system
observed in the hyper-luminous quasar J1538+ 0855 at z= 3.6. Observations from the Sloan …