Related papers: QSO obscuration at high redshift ($z \gtrsim 7$): …
Quasars are the most luminous of active galactic nuclei (AGN), and are perhaps responsible for quenching star formation in their hosts. The Stripe 82X catalog covers 31.3 deg$^2$ of the Stripe 82 field, of which the 15.6 deg$^2$ covered…
The absence of high Eddington ratio, obscured Active Galactic Nuclei (AGN) in local ($z\lesssim0.1$) samples of moderate luminosity AGN has generally been explained to result from radiation pressure on the dusty gas governing the level of…
We demonstrate that the luminosity function of the recently detected population of star-forming galaxies and the QSO luminosity function at z=3 can be matched with the mass function of dark matter haloes predicted by hierarchical…
Using the wide multi-band photometry available in the COSMOS field we explore the host galaxy properties of a large sample of Active Galactic Nuclei (AGN) obtained by combining X-ray and optical spectroscopic selections. Based on a careful…
At the highest redshifts, z>6, several tens of luminous quasars have been detected. The search for fainter AGN, in deep X-ray surveys, has proven less successful, with few candidates to date. An extrapolation of the relationship between…
(Abriged) We report on the measurement of the rest frame K-band luminosity and total stellar mass of the hosts of 89 broad line Active Galactic Nuclei detected in the zCOSMOS survey in the redshift range 1<z<2.2. The unprecedented…
We build a simple physical model to study the high-redshift active galactic Nucleus (AGN) evolution within the co-evolution framework of central black holes (BHs) and their host galaxies. The correlation between the circular velocity of a…
Obscured or narrow-line active galaxies offer an unobstructed view of the quasar environment in the presence of a luminous and vigorously accreting black hole. We exploit the large new sample of optically selected luminous narrow-line…
We use NIRSpec/MSA spectroscopy and NIRCam imaging to study a sample of 18 massive ($\log\; M_{*}/M_{\odot} \gt 10\;$dex), central quiescent galaxies at $2\leq z \leq 5$ in the GOODS fields, to investigate their number density,…
We present the first results from the KMOS AGN Survey at High redshift (KASHz), a VLT/KMOS integral-field spectroscopic survey of z>0.6 AGN. We present galaxy-integrated spectra of 89 X-ray AGN (Lx=10^42-10^45 erg/s), for which we observed…
Our current understanding of the evolution of obscured accretion onto supermassive black holes is reviewed. We consider the literature results on the relation between the fraction of moderately obscured, Compton-thin AGN and redshift, and…
We analyse the redshift dependence of space number density of quasars assuming that they are the short-lived active stages of the massive galaxies and arise immediately after the collapse of homogeneous central part of protogalaxy clouds.…
High-redshift quasars are believed to reside in massive halos in the early universe and should therefore be located in fields with overdensities of galaxies, which are thought to evolve into galaxy clusters seen in the local universe.…
New populations of hyper-luminous, dust-obscured quasars have been recently discovered around the peak epoch of galaxy formation ($z \sim 2-3$), in addition to similar sources found at lower redshifts. Such dusty quasars are often…
We present the results of fitting deep off-nuclear optical spectroscopy of radio-quiet quasars, radio-loud quasars and radio galaxies at z ~ 0.2 with evolutionary synthesis models of galaxy evolution. Our aim was to determine the age of the…
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…
We report high spatial resolution (~0.076", 410pc) Atacama Large Millimeter/submillimeter Array imaging of the dust continuum and the ionized carbon line [CII] in a luminous quasar host galaxy at z=6.6, 800 million years after the big bang.…
Quasars (QSOs) hosting supermassive black holes are believed to reside in massive halos harboring galaxy overdensities. However, many observations revealed average or low galaxy densities around $z\gtrsim6$ QSOs. This could be partly…
Supermassive Black Holes (BHs) are known to efficiently grow through gas accretion, but even sustained and intense mass build-up through this mechanism struggles to explain the assembly of the most massive BHs observed in the local…
Large-scale surveys over the last years have revealed about 300 QSOs at redshift above 6. Follow-up observations identified surprising properties, such as the very high black hole (BH) masses, spatial correlations with surrounding cold gas…