The Intermediate Line Region in AGN: a region "praeter necessitatem"?

As a consequence of improved S/N, spectral resolution and wavelength coverage various authors have introduced, without strong justification, new emitting regions to account for various emission line profile differences in AGN. The so-called CIVlambda1549 intermediate line region (ILR) appears to be especially ill-defined. We present observational evidence that suggests the ILR is statistically indistinguishable from the classical narrow line region (NLR). We present the results of theoretical models showing that a smooth density gradient in the NLR can produce CIV and Balmer emission lines with different widths. The putative ILR component has often been included with the broad line profile in studies of CIV BLR properties. Failure to account for the composite nature of CIV emission, and for the presence of sometimes appreciable NLR CIV emission, has important consequences for our understanding of the BLR.Comment: 3 Figs. 1 Table, accepted for publication in Astrophysical Journal Letter

Balmer line shifts in quasars

We offer a broad review of Balmer line phenomenology in type 1 active galactic nuclei, briefly sum- marising luminosity and radio loudness effects, and discussing interpretation in terms of nebular physics along the 4D eigenvector 1 sequence of quasars. We stress that relatively rare, peculiar Balmer line profiles (i.e., with large shifts with respect to the rest frame or double and multiple peaked) that start attracted attentions since the 1970s are still passable of multiple dynamical interpretation. More mainstream objects are still not fully understood as well, since competing dynamical models and geometries are possible. Further progress may come from inter-line comparison across the 4D Eigenvector 1 sequence.Comment: Accepted for publication in Astrophysics and Space Science, Special Issue on Line Shifts in Astrophysics and Laboratory Plasm

A new method to obtain the Broad Line Region size of high redshift quasars

We present high S/N UV spectra for eight quasars at z $\sim$ 3 obtained with VLT/FORS. The spectra enable us to analyze in detail the strong and weak emission features in the rest-frame range 1300-2000 A of each source (Ciii]$\lambda$1909, Siiii]$\lambda$1892, Aliii$\lambda$1860, Siii$\lambda$1814, Civ$\lambda$1549 and blended Siiv$\lambda$1397+Oiv]$\lambda$1402). Flux ratios Aliii$\lambda$1860/Siiii]$\lambda$1892, Civ$\lambda$1549/Aliii$\lambda$1860, Siiv$\lambda$1397+Oiv]$\lambda$1402/Siiii]$\lambda$1892 and Siiv$\lambda$1397+Oiv]$\lambda$1402/Civ$\lambda$1549 strongly constrain ionizing photon flux and metallicity through the use of diagnostic maps built from CLOUDY simulations. The radius of the broad line region is then derived from the ionizing photon flux applying the definition of the ionization parameter. The rBLR estimate and the width of a virial component isolated in prominent UV lines yields an estimate of black hole mass. We compare our results with previous estimates obtained from the rBLR - luminosity correlation customarily employed to estimate black hole masses of high redshift quasars.Comment: arXiv admin note: substantial text overlap with arXiv:1011.424