Related papers: Compton Thick AGN in the XMM-COSMOS survey

The spectrum of the hard X-ray background records the history of accretion processes integrated over the cosmic time. Several pieces of observational and theoretical evidence indicate that a significant fraction of the energy density is…

Obscured AGN are fundamental to understand the history of Super Massive Black Hole growth and their influence on galaxy formation. However, the Compton-thick AGN (NH>1e24 cm^-2) population is basically unconstrained, with less than few…

The Chandra Deep Field is the region of the sky with the highest concentration of X-ray data available: 4Ms of Chandra and 3Ms of XMM data, allowing excellent quality spectra to be extracted even for faint sources. We take advantage of this…

This work discusses the broadband X-ray spectral analysis of 11 candidate heavily-obscured active galactic nuclei (AGN) selected based on their infrared and X-ray properties by a recently published machine learning algorithm. This paper is…

We present the results of calculations of the cosmic AGN background spectrum from 3 keV (4\times 10^{-4} microns) to 1000 microns. These computations make use of the measured X-ray luminosity function and its evolution, as well as fits from…

We present a selection technique to detect Compton-thick (CT) active galactic nuclei (AGNs) in the 3XMM/SDSS-DR7 cross-correlation. A subsample of 3481 X-ray sources that are detected in the hard band (2-8 keV) and have photometric…

The cosmological evolution of supermassive black holes (SMBHs) seems to be intimately linked to their host galaxies. Active galactic nuclei (AGN) can be probed by deep X-ray surveys. We review results from large X-ray selected samples…

Previous studies of the active galactic nuclei (AGN) contribution to the cosmic X-ray background (CXB) consider only observable parameters such as luminosity and absorbing column. Here, for the first time, we extend the study of the CXB to…

(ABRIDGED) We investigate here the XLF of absorbed (Nh between 4E21 and E24 cm-2) and unabsorbed (Nh < 4E21 cm-2) AGN, the fraction of absorbed AGN as a function of Lx (and z), the intrinsic Nh distribution of the AGN population, and the…

We present the analysis of simultaneous NuSTAR and XMM-Newton data of 8 Compton-thick (CT-) active galactic nuclei (AGN) candidates selected in the Swift-Burst Alert Telescope (BAT) 100 month survey. This work is part of an ongoing effort…

Highly obscured active galactic nuclei (AGN) are common in nearby galaxies, but are difficult to observe beyond the local Universe, where they are expected to significantly contribute to the black hole accretion rate density. Furthermore,…

We provide X-ray constraints and perform the first X-ray spectral analyses for bright (f_850>=5mJy; S/N>=4) SCUBA sources in an 8.4'x8.4' area of the 2 Ms Chandra Deep Field-North survey containing the Hubble Deep Field-North. X-ray…

X-ray surveys are one of the most unbiased methods for detecting Compton Thick (CT; $N_{{\mathrm{H}}} \geq 10^{24}$ cm$^{-2}$) AGN, which are thought to comprise up to $60\%$ of AGN within $z \lesssim 1.0$. These CT AGN are often difficult…

It is well accepted that unabsorbed as well as absorbed AGN are needed to explain the nature and the shape of the Cosmic X-ray background, even if the fraction of highly absorbed objects (dubbed Compton-thick sources) substantially still…

(abridged)The majority of Active Galactic Nuclei (AGN) suffer from significant obscuration by surrounding dust and gas. X-ray surveys in the 2-10 keV band will miss the most heavily-obscured AGN in which the absorbing column density exceeds…

Based on current models of the Cosmic X-ray Background (CXB), heavily obscured Active Galactic Nuclei (AGN) are expected to make up ~10% of the peak emission of the CXB and ~20% of the total population of AGN, yet few of these sources have…

We identify sources with extremely hard X-ray spectra (i.e., with photon indices of Gamma<0.6 in the 13 sq. deg. NuSTAR serendipitous survey, to search for the most highly obscured AGNs detected at >10 keV. Eight extreme NuSTAR sources are…

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…

According to the latest versions of synthesis modeling of the Cosmic X-ray Background, Compton Thick AGN should represent ~50% of the total absorbed AGN population. However, despite their importance in the cosmological context, only a few…

The XLF of AGN offers a robust tool to study the evolution and the growth of SMBHs over cosmic time. Owing to the limited area probed by X-ray surveys, optical surveys are routinely used to probe the accretion in the high redshift Universe…