929 citations · 3.5k across the 40 of their papers we have counts for
10 papers · 2 filters
BeppoSAX Observations of 1-Jy BL Lacertae Objects - II
P. Padovani, L. Costamante, P. Giommi +3
We present new BeppoSAX LECS and MECS observations, covering the energy range 0.1 - 10 keV (observer's frame), of four BL Lacertae objects selected from the 1 Jy sample. All source…
The HELLAS2XMM 1dF survey: on the nature of high X-ray to optical flux ratio sources
F. Fiore, M. Brusa, F. Cocchia +12
We present results from the photometric and spectroscopic identification of 122 X-ray sources discovered by XMM-Newton in the 2-10 keV band (the HELLAS2XMM 1dF sample). One of the…
Restless Quasar Activity: From BeppoSAX to Chandra and XMM-Newton
C. Vignali, A. Comastri, W. N. Brandt
We briefly review some of the progress made in the last decade in the study of the X-ray properties of the quasar population from the luminous, local objects observed by BeppoSAX t…
High Redshift Supermassive Black Holes: X-ray observations
Andrea Comastri, the Hellas2Xmm team
The spectrum of the hard X-ray background records the history of accretion processes integrated over the cosmic time. Several observational and theoretical evidences indicate that…
The Hellas2XMM survey: III. Multiwavelength observations of hard X-ray selected sources in the PKS 0312-77 field
M. Brusa, A. Comastri, M. Mignoli +11
We present extensive optical, radio and infrared follow-up observations of a sample of 35 hard X-ray (2-10 keV) selected sources discovered serendipitously in the PV XMM-Newton obs…
Elusive Active Galactic Nuclei
R. Maiolino, A. Comastri, R. Gilli +8
A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically "elusive". X-ray observations are an optima…