Related papers: The X-ray spectrum of Compton-thick Seyfert 2 Gala…
Results from BeppoSAX observations of Compton--thick Seyfert 2 galaxies are summarized and reviewed, and their general properties derived and discussed. In five out of the seven observed sources, the nucleus is directly visible at high…
A synthesis model for the cosmic X-ray Background (XRB) is presented, which includes a proper treatment of Compton scattering in the absorbing matter for type 2 AGN. Evidence for a decrease of the relative importance of type 2 AGN at high…
We present a sample of 17 type 2 Seyfert galaxies which have an X-ray column density lower than 10^{22} cm^{-2}. The Compton thin nature of these sources is strongly suggested by isotropic indicators. We estimate the fraction of these…
A modification of the popular unification model for Seyfert galaxies is proposed, which takes into account recent observational findings on the statistical properties of both type 1 and type 2 Seyferts. In the proposed scenario,…
We discuss the properties of a small sample of Seyfert 2 galaxies whose X-ray spectrum changed appearance on time scales of years, becoming reflection-dominated from Compton-thin, or viceversa. A reflection--dominated spectrum is usually…
We present a composite 1-10 keV Seyfert 2 X-ray spectrum, derived from ASCA observations of a distance-limited sample of nearby galaxies. All 29 observed objects were detected. Above ~3 keV, the composite spectrum is inverted, confirming…
We present an X-ray spectroscopic study of optically selected (SDSS) Seyfert 2 (Sy2) galaxies. The goal is to study the obscuration of Sy2 galaxies beyond the local universe, using good quality X-ray spectra in combination with high S/N…
We use hard X-ray data for an "optimal" sample of Seyfert 2 galaxies to derive the distribution of the gaseous absorbing column densities among obscured active nuclei in the local Universe. Of all Seyfert 2 galaxies in the sample, 75% are…
We present new spectropolarimetry of a sample of nearby Compton-thin Seyfert 2 galaxies (ie those with N_H<10^23 cm^-2). We show that the detection rate of scattered broad Halpha in this sample is considerably higher than in Seyfert 2…
Recent results on the X-ray spectrum and variability of Seyfert 1 galaxies are reviewed. New spectral results from BeppoSAX observations are also presented and briefly discussed.
We present an X-ray spectral analysis of a sample of 8 bona-fide Seyfert 2 galaxies, selected on the basis of their high $[OIII]\lambda5007$ flux, from the Ho et al. (1997) spectroscopic sample of nearby galaxies. We find that, in general,…
X-ray spectra transmitted through matter which is optically thick to Compton scattering are computed by means of Monte Carlo simulations. Applications to the BeppoSAX data of the Seyfert 2 galaxy in Circinus, and to the spectral modeling of…
We study the X-ray spectra of a sample of 19 obscured, optically-selected Seyfert galaxies (Sy 1.8, 1.9 and 2) in the local universe ($d \leq 175$~Mpc), drawn from the CfA Seyfert sample. Our analysis is driven by the high sensitivity of…
Recent work by Risaliti et al.(1999) suggests that more than half of all Seyfert 2 galaxies in the local universe are Compton-thick (N_H > 10^24 cm^-2). This has implications for AGN synthesis models for the X-ray background (XRB), the…
We present a summary of spectra of Seyfert galaxies observed by the OSSE detector aboard Compton Gamma Ray Observatory. We obtain average spectra of Seyferts of type 1 and 2, and find they are well fitted by thermal Comptonization. We…
We present the combined Chandra and Swift-BAT spectral analysis of seven Seyfert 2 galaxies selected from the Swift-BAT 100-month catalog. We selected nearby (z<=0.03) sources lacking of a ROSAT counterpart and never previously observed…
We present Suzaku observations of five hard X-ray selected nearby Seyfert 2 galaxies. All the sources were clearly detected with the pin Hard X-ray Detector up to several tens of keV, allowing for a fairly good characterization of the…
Obscured active galactic nuclei, which are classified optically as type 2 (narrow-line) Seyfert galaxies in the local universe, are by far the most promising candidates for the origin of the hard (2-10 keV) X-ray background radiation.…
We present XMM-Newton spectral analysis of all 38 Seyfert galaxies from the Palomar spectroscopic sample of galaxies. These are found at distances of up to 67 Mpc and cover the absorbed 2-10 keV luminosity range ~10^38-10^43 ergs/s. Our aim…
BeppoSAX results on Seyfert galaxies are reviewed and discussed.