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16 papers · 2 filters
The circumnuclear X-ray reflectors in NGC 1068 and the Circinus Galaxy
Stefano Bianchi, Giorgio Matt, Kazushi Iwasawa
The ASCA and BeppoSAX spectra of the Circinus Galaxy and NGC 1068 are analysed and compared with photoionization models based on cloudy. In the case of Circinus, a single, mildly i…
The BeppoSAX observation of Mrk 766
Giorgio Matt, G. C. Perola, F. Fiore +3
The Narrow Line Seyfert 1 galaxy Mrk 766 has been observed by BeppoSAX on May 1997. The source was fairly variable, both in flux and spectrum, during the observation. The variabili…
On the peculiar X-ray properties of the bright nearby radio-quiet quasar PDS456
C. Vignali, A. Comastri, F. Nicastro +3
BeppoSAX and ASCA observations of the nearby (z=0.184), high-luminosity, radio-quiet quasar PDS456 are presented. The X-ray spectrum is characterized by a prominent ionized edge at…
Multiple BeppoSAX Observations of IC 4329A to Probe the Origin of the Compton Reflection Component in Seyfert 1 Galaxies
M. Cappi, G. Di Cocco, M. Dadina +5
IC 4329A is the brightest known Seyfert galaxy in hard (~2-30 keV) X-rays and is likely to be representative of Seyfert 1 galaxies as a class. A recent 100 ks BeppoSAX observation…
The BeppoSAX HELLAS survey: on the nature of faint hard X-ray selected sources
F. Fiore, L. A. Antonelli, P. Ciliegi +8
The BeppoSAX 4.5-10 keV High Energy Large Area Survey has covered about 80 square degrees of sky down to a flux of F(5-10keV)~5E-14 cgs. Optical spectroscopic identification of abo…
Resolving the 10-40 keV Cosmic X-ray Background with Constellation-X
Giorgio Matt, Fulvio Pompilio, Fabio La Franca
The energy density of the Cosmic X-ray background (XRB) peaks around 30 keV (see Figure 1), an energy not yet probed by focussing imaging instruments. The first hard X-ray telescop…
The broad band spectrum and variability of Seyfert 1
Giorgio Matt
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.
A Self-Consistent Test of Comptonisation Models Using Bepposax Observations of Seyfert Galaxies
P. O. Petrucci, F. Haardt, L. Maraschi +6
We test accurate models of Comptonisation spectra over BeppoSAX observations of Seyfert galaxies focusing on the long look at NGC 5548. The hot plasma temperature derived with thes…
Sub-mm and X-ray background: two unrelated phenomena?
P. Severgnini, R. Maiolino, M. Salvati +9
Obscured AGNs are thought to contribute a large fraction of the hard X-ray background (2-10 keV), and have also been proposed as the powerhouse of a fraction of the SCUBA sources w…
BeppoSAX observations of Mrk 509 and MCG+8-11-11
G. C. Perola, G. Matt, F. Fiore +7
BeppoSAX observations of the Seyfert galaxies Mrk 509 and MCG+8-11-11 are presented. Earlier evidence of a soft excess in Mrk 509 is confirmed. This excess is found to be better re…
BeppoSAX observations of AM Herculis in intermediate and high states
G. Matt, D. de Martino, B. T. Gaensicke +5
Temporal and spectral analyses from BeppoSAX observations of AM Her performed during both an intermediate and a high state are presented and discussed. Optical observations taken a…
Spectroscopic identification of ten faint hard X-ray sources discovered by Chandra
F. Fiore, F. La Franca, C. Vignali +6
We report optical spectroscopic identifications of 10 hard (2-10 keV) X-ray selected sources discovered by Chandra. The X-ray flux of the sources ranges between 1.5 and 25 x 10-14…
Hard X-ray emission from the galaxy cluster A2256
R. Fusco-Femiano, D. Dal Fiume, S. De Grandi +6
After the positive detection by BeppoSAX of hard X-ray radiation up to ~80 keV in the Coma cluster spectrum, we present evidence for nonthermal emission from A2256 in excess of the…
Dust lanes, thick absorbers, and the unification model for Seyfert galaxies
Giorgio Matt
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…
A Long Observation of NGC 5548 by BeppoSAX: the High Energy Cut-off, Intrinsic Spectral Variability and a Truly Warm Absorber
F. Nicastro, L. Piro, A. De Rosa +11
NGC 5548 was observed by BeppoSAX in a single long (8 day) observation from 0.2 to 200 keV. We find (1) the spectral variation of the source is produced by a change of the intrinsi…
The BeppoSAX High Energy Large Area Survey (HELLAS): a progress Report
A. Comastri, F. Fiore, C. Vignali +2
The integrated emission of highly obscured AGN is expected to provide a major contribution to the X-ray energy density in the Universe: the X-ray background (XRB). The study of the…