3,865 research outputs found
Compton-thick AGN and the Synthesis of the Cosmic X-ray Background: the Suzaku Perspective
We discuss the abundance of Compton-thick AGN as estimated by the most recent
population synthesis models of the cosmic X-ray background. Only a small
fraction of these elusive objects have been detected so far, in line with the
model expectations. The advances expected by the broad band detectors on board
Suzaku are briefly reviewed.Comment: proceedings of "The Extreme Universe in the Suzaku Era", Kyoto 4-8
December 2006, to be published in Progress of Theoretical Physics, Supplemen
ASCA view on High-Redshift Radio-Quiet Quasars
We briefly discuss the latest ASCA results on the X-ray spectral properties
of high-redshift radio-quiet quasars.Comment: 4 pages, 1 figure, to appear in the Proceedings of the Conference
"X-ray Astronomy '999: Stellar Endpoints, AGNs, and the Diffuse X-ray
Background (September 6-10 - 1999
A deep look at the inner regions of the mini-BAL QSO PG 1126-041 with XMM-Newton
A long XMM-Newton observation of the mini-BAL QSO PG 1126-041 allowed us to
detect a highly ionized phase of X-ray absorbing gas outflowing at v~15000
km/s. Physical implications are briefly discussed.Comment: 2 pages, 2 figures. Proceedings of "X.ray Astronomy 2009", Bologna
09/7-11/2009, AIP Conference Series, Eds. A. Comastri, M. Cappi, L. Angelin
Broad-band X-ray analysis of local mid-infrared selected Compton-thick AGN candidates
The estimate of the number and space density of obscured AGN over cosmic time
still represents an open issue. While the obscured AGN population is a key
ingredient of the X-ray background synthesis models and is needed to reproduce
its shape, a complete census of obscured AGN is still missing. Here we test the
selection of obscured sources among the local 12-micron sample of Seyfert
galaxies. Our selection is based on a difference up to three orders of
magnitude in the ratio between the AGN bolometric luminosity, derived from the
spectral energy distribution (SED) decomposition, and the same quantity
obtained by the published XMM-Newton 2-10 keV luminosity.
The selected sources are UGC05101, NGC1194 and NGC3079 for which the
available X-ray wide bandpass, from Chandra and XMM-Newton plus NuSTAR data,
extending to energies up to ~30-45 keV, allows us an accurate determination of
the column density, and hence of the true intrinsic power.
The newly derived NH values clearly indicate heavy obscuration (about 1.2,
2.1 and 2.4 x10^{24} cm-2 for UGC05101, NGC1194 and NGC3079, respectively) and
are consistent with the prominent silicate absorption feature observed in the
Spitzer-IRS spectra of these sources (at 9.7 micron rest frame). We finally
checked that the resulting X-ray luminosities in the 2-10 keV band are in good
agreement with those derived from the mid-IR band through empirical L_MIR-L_X
relations.Comment: 14 pages, 6 figures, accepted for publication in MNRA
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