Related papers: The Intrinsic Quasar Luminosity Function: Accounti…
We have investigated effects of dust attenuation on quasar luminosity functions using a semi-analytic galaxy formation model combined with a large cosmological N-body simulation. We estimate the dust attenuation of quasars self-consistently…
We have developed a consistent analytical model to describe the observed evolution of the quasar luminosity function. Our model combines black hole mass distributions based on the Press - Schechter theory of the structure formation in the…
The possibility that stellar mass primordial black holes may make up at least a significant fraction of dark matter has recently received much attention, partly as a result of gravitational wave observations, but more specifically from…
Recent discoveries by the Sloan Digital Sky Survey (SDSS) of four bright redshift z=6 quasars could constrain the mechanism by which the supermassive black holes powering these sources are assembled. Here we compute the probability that the…
Measurements of the physical properties of accretion disks in active galactic nuclei are important for better understanding the growth and evolution of supermassive black holes. We present the accretion disk sizes of 22 quasars from…
We compare the microlensing-based continuum emission region size measurements in a sample of 15 gravitationally lensed quasars with estimates of luminosity-based thin disk sizes to constrain the temperature profile of the quasar continuum…
We consider the observational properties of a static black hole space-time immersed in a dark matter envelope. We thus investigate how the modifications to geometry, induced by the presence of dark matter affect the luminosity of the black…
Quasars are bright active galactic nuclei powered by the accretion of matter around supermassive black holes at the center of galaxies. Their stochastic brightness variability depends on the physical properties of the accretion disk and…
Though the bulk of the observed optical flux from the discs of intermediate-redshift lensed quasars is formed well outside the region of strong relativistic boosting and light-bending, relativistic effects have important influence on…
The observed enhancement of the Fe K$\alpha$ line in three gravitationally lensed QSOs (MG J0414+0534, QSO 2237+0305, H1413+117) is interpreted in terms of microlensing, even when equivalent X-ray continuum amplification is not observed. In…
Because quasars are unresolved in optical imaging, their structures must presently be inferred. Gravitational microlensing offers the possibility to produce information about the luminous structure provided the Einstein ring diameter of the…
The X-ray luminosity function of distant (3<z<5.1) unabsorbed quasars has been measured. A sample of distant high-luminosity quasars ($10^{45} \leq L_{{\rm X},2-10} < 7.5 \times 10^{45}$ erg/s in the 2--10 keV energy band) from the catalog…
(Abridged) Based on numerical simulations of galaxy mergers that incorporate black hole (BH) growth, we predict the faint end slope of the quasar luminosity function (QLF) and its evolution with redshift. Our simulations have yielded a new…
We use the microlensing variability observed for nine gravitationally lensed quasars to show that the accretion disk size at 2500 Angstroms is related to the black hole mass by log(R_2500/cm) = (15.6+-0.2) + (0.54+-0.28)log(M_BH/10^9M_sun).…
We use thirteen seasons of R-band photometry from the 1.2m Leonard Euler Swiss Telescope at La Silla to examine microlensing variability in the quadruply-imaged lensed quasar WFI 2026-4536. The lightcurves exhibit ${\sim}\,0.2\,\text{mag}$…
We provide a simple theoretical model for the quasar luminosity function at high redshifts that naturally reproduces the statistical properties of the luminous SDSS quasar sample at redshifts z~4.3 and z>5.7. Our model is based on the…
I present mass functions of actively accreting black holes detected in different quasar surveys which in concert cover a wide range of cosmic history. I briefly address what we learn from these mass functions. I summarize the motivation for…
We use 62185 quasars from the Sloan Digital Sky Survey Data Release 5 sample to explore the relationship between black hole mass and luminosity. Black hole masses were estimated based on the widths of their H{\beta}, MgII and CIV lines and…
We develop a general method for analyzing the light curves of microlensed quasars and apply it to the OGLE light curves of the four-image lens Q2237+0305. We simultaneously estimate the effective source velocity, the average stellar mass,…
We place a limit on the logarithmic slope of the luminous quasar luminosity function at z~6 of beta>-3.0 (90%) using gravitational lensing constraints to build on the limit of beta>-3.3 (90%) derived from an analysis of the luminosity…