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A model for the X-ray absorption in Compton--thin AGN
Alessandra Lamastra, G. Cesare Perola, Giorgio Matt
The fraction of AGN with photoelectric absorption in the X-rays ranging from NH of 10^{22} up to about 10^{24} cm^{-2} (Compton-thin) appears observationally to be anticorrelated t…
A Compton reflection dominated spectrum in a peculiar accreting neutron star
Nanda Rea, Luigi Stella, Gian Luca Israel +5
We report on a puzzling event occurred during a long BeppoSAX observation of the slow-rotating binary pulsar GX 1+4. During this event, lasting about 1 day, the source X-ray flux w…
The HELLAS2XMM survey. IX. Spectroscopic identification of super-EROs hosting AGNs
R. Maiolino, M. Mignoli, L. Pozzetti +12
We present VLT near-IR spectroscopic observations of three X-ray sources characterized by extremely high X-ray-to-optical ratios (X/O>40), extremely red colors (6.3<R-K<7.4, i.e. E…
The HELLAS2XMM survey. VII. The hard X-ray luminosity function of AGN up to z=4: more absorbed AGN at low luminosities and high redshifts
F. La Franca, F. Fiore, A. Comastri +14
We have determined the cosmological evolution of the density of AGN and of their Nh distribution as a function of the un-absorbed 2-10 keV luminosity up to redshift 4. We used the…
Clearing up the clouds around NGC 4151: evidence of a highly ionized absorber
L. Piro, A. De Rosa, G. Matt +1
The Seyfert 1 galaxy NGC4151 is characterized by complex X-ray absorption, well described by a dual absorber, composed of a uniform mildly ionized gas and a cold system that partia…
Highly ionized iron absorption lines from outflowing gas in the X-ray spectrum of NGC 1365
G. Risaliti, S. Bianchi, G. Matt +4
We present the discovery of four absorption lines in the X-ray spectrum of the Seyfert Galaxy NGC 1365, at energies between 6.7 and 8.3 keV. The lines are detected with high statis…