Involved people at OAB: Stirpe, de Ruiter, Zitelli.
In collaboration with A. Robinson and D. Axon the studies on the statistics of broad emission lines in AGN have been continued. In particular, work has started on analyzing the spectra of the H-Beta region, which involves a complex series of de-blending and fitting operations. They are attempting to automate the process by writing an interactive program in the IDL language.
Stirpe and de Ruiter are involved in long term monitoring programs to study the variability of emission lines and continuum in Seyfert galaxies. Stirpe has participated in the International AGN Watch monitoring of the Narrow Line Seyfert 1 galaxy Akn 564, which was the target of an RXTE campaign in 1999. The Loiano 1.5m telescope provided differential photometry for the parallel ground-based campaign, detecting continuum variations of about 5%.
De Ruiter, in collaboration with Lub (Leiden Observatory) constructed a database containing many hundreds of photometric and spectroscopic measurements for a sample of about 15 type 1 and type 2 Seyferts in the southern hemisphere, based on almost 15 years of observations. The data are expected to be submitted for publication by the middle of 2000.
In collaboration with P. Focardi, B.Kelm (University of Bologna) and T.Venturi
(Institute of Radio Astronomy CNR, Bologna) Zitelli is studying the relationship between
nuclear activity and environment for active galactic nuclei. There is strong evidence that
the environments of Active Galactic Nuclei are complex, in the local universe but also
up to 
. Although it is well established that radio loud quasars,
radio galaxies and BLlacs reside in denser than average regions, the role of
the environment and of interactions on Seyfert galaxies is to some extent still
controversial.
The complexity of the discussion increases because the samples used are
limited in number. To improve the statistical uncertainty a
strategy was adopted based on statistically significant samples of nearby AGNs and an
appropriate control sample, selected on the basis of criteria that are independent
of morphology and environmental properties. The global properties of
active galactic nuclei are compared with those of a sample of "normal"galaxies,
in particular the excess of perturbed Seyferts in small systems with
respect to normal galaxies.
This study, started one year ago, is still in progress.