Related papers: The Chandra COSMOS Legacy survey: the z>3 sample

We present an analysis of the X-ray Active Galactic Nucleus (AGN) population in a sample of seven massive galaxy clusters in the redshift range $0.35<z<0.45$. We utilize high-quality Chandra X-ray imaging to robustly identify AGN and…

We estimate the abundance of Compton-thick (CT) active galactic nuclei (AGN) based on our joint model of X-ray and infrared backgrounds. At L_{rest 2-10 keV} > 10^42 erg/s, the CT AGN density predicted by our model is a few 10^-4 Mpc^-3…

We present the combined Chandra and Swift-BAT spectral analysis of nine low-redshift (z <= 0.10), candidate heavily obscured active galactic nuclei (AGN) selected from the Swift-BAT 150-month catalog. We located soft (1-10 keV) X-ray…

We investigate the evolution of the hard X-ray luminosity of the red galaxy population using a large sample of 3316 red galaxies selected over a wide range in redshift (0.3<z<0.9) from a 1.4 deg^2 region in the Bootes field of the NOAO Deep…

We present the results of optical spectroscopic identifications of a bright subsample of 2-10keV hard X-ray selected sources from the ASCA Medium Sensitivity Survey in the northern sky. The flux limit of the subsample is 3*10^-13 erg s^-1…

We present the analysis and results of a spectroscopic follow-up program of a mass-selected sample of six galaxies at 3 < z < 4 using data from Keck-NIRSPEC and VLT-Xshooter. We confirm the z > 3 redshifts for half of the sample through the…

We present the space density evolution, from z=1.5 up to z=5.5, of the most massive (M$\geq10^9$M$_{\odot}$) black holes hosted in jetted Active Galactic Nuclei(AGNs). The analysis is based on a sample of 380 luminosity-selected…

Heavily obscured, Compton Thick (CT, NH>10^24 cm^-2) AGN may represent an important phase in AGN/galaxy co-evolution and are expected to provide a significant contribution to the cosmic X-ray background (CXB). Through direct X-ray spectra…

We investigate the X-ray number counts in the 1-2 Ms Chandra Deep Fields (CDFs) to determine the contributions of faint X-ray source populations to the extragalactic X-ray background (XRB). X-ray sources were separated into Active Galactic…

We describe X-ray observations with Chandra and XMM-Newton of 18 galaxy groups (M_group ~ 1-6x10^13 Msolar, z~0.05) from the Zurich Environmental Study (ZENS). We aim to establish the frequency and properties, unaffected by host galaxy…

As a result of deep hard X-ray observations by Chandra and XMM-Newton a significant fraction of the cosmic X-ray background (CXRB) has been resolved into individual sources. These objects are almost all active galactic nuclei (AGN) and…

The abundance of active galactic nuclei (AGN) in cosmic voids is relatively unexplored in the literature, but can potentially provide new constraints on the environmental dependence of AGN activity and the AGN-host co-evolution. We…

The study of the space density of bright AGNs at $z>4$ has been subject to extensive effort given its importance for the estimate of the cosmological ionizing emissivity and growth of supermassive black holes. In this context we have…

We have identified a large-scale structure at z~0.73 in the COSMOS field, coherently described by the distribution of galaxy photometric redshifts, an ACS weak-lensing convergence map and the distribution of extended X-ray sources in a…

We present X-ray point-source catalogs for a deep 400 ks Chandra ACIS-I exposure of the SSA22 field. The observations are centred on a z = 3.09 protocluster, which is populated by Lyman break galaxies (LBGs), Lyalpha emitters (LAEs), and…

We present the X-ray spectroscopic study of the Compton-thick (CT) active galactic nuclei (AGN) population within the $\textit{Chandra}$ Deep Field South (CDF-S) by using the deepest X-ray observation to date, the $\textit{Chandra}$ 7 Ms…

We present a new measurement of the space density of high redshift (3.0<z<4.5), X-ray selected QSOs obtained by exploiting the deep and uniform multiwavelength coverage of the COSMOS survey. We have assembled a statistically large (40…

We investigate the evolution over the last 6.3 Gyr of cosmic time (i.e., since z ~ 0.7) of the average X-ray properties of early-type galaxies within the Extended Chandra Deep Field-South (E-CDF-S). Our early-type galaxy sample includes 539…

SMBHs are theorised to undergo significant growth in the early Universe, however, the X-ray Luminosity Function (XLF), used as a principal tracer of the SMBH accretion density, lacks observational constraints at z>6, until now. We present…

Context: Redshifts are fundamental for our understanding of extragalactic X-ray sources. Ambiguous counterpart associations, expensive optical spectroscopy and/or multimission multiwavelength coverage to resolve degeneracies make estimation…