Related papers: A Robust Determination of the size of quasar accre…
Gravitational microlensing is a powerful tool for probing the physical properties of quasar accretion disks and properties of the lens galaxy such as its dark matter fraction and mean stellar mass. Unfortunately the number of lensed quasars…
We analyze V, I and H band HST images and two seasons of R-band monitoring data for the gravitationally lensed quasar SDSS0924+0219. We clearly see that image D is a point-source image of the quasar at the center of its host galaxy. We can…
Many analyses have concluded that the accretion disc sizes measured from the microlensing variability of quasars are larger than the expectations from the standard thin disc theory by a factor of $\sim4$. We propose a simply model by…
We show how analysis of a quasar high-magnification microlensing event may be used to construct a map of the frequency-dependent surface brightness of the quasar accretion disk. The same procedure also allows determination of the disk…
We investigate the discrepancy between the predicted size of accretion disks (ADs) in quasars and the observed sizes as deduced from gravitational microlensing studies. Specifically, we aim to understand whether the discrepancy is due to an…
Based on the microlensing variability of the two-image gravitational lens HE1104-1805 observed between 0.4 and 8 microns, we have measured the size and wavelength-dependent structure of the quasar accretion disk. Modeled as a power law in…
We study three high magnification microlensing events, generally recognized as probable caustic crossings, in the optical light curves of the multiply imaged quasar Q 2237+0305. We model the light curve of each event as the convolution of a…
Powered by supermassive black holes at their centers, quasars are among the most luminous objects in the Universe, serving as important probes of cosmic history and galaxy evolution. The size of the accretion disc surrounding the black hole…
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,…
Using a microlensing analysis of 11-years of OGLE V-band photometry of the four image gravitational lens Q2237+0305, we measure the inclination i of the accretion disk to be cos i > 0.66 at 68% confidence. Very edge on (cos i < 0.39)…
Gravitational microlensing by the stellar population of lensing galaxies provides an important opportunity to spatially resolve the accretion disk structure in strongly lensed quasars. Some of the objects (like Einstein's cross) are…
Two years' worth of u-, g-, r-, i-, and z-band optical light curves were obtained for the massive type 1 quasar PG 2308+098 at z=0.433 using the 1.05-m Kiso Schmidt telescope/Kiso Wide Field Camera, and inter-band time lags of the light…
Observations of gravitational microlensing in multiply imaged quasars currently provide the only direct probe of quasar emission region structure on sub-microarcsecond scales. Analyses of microlensing variability are observationally…
We analyzed the microlensing of the X-ray and optical emission of the lensed quasar PG 1115+080. We find that the effective radius of the X-ray emission is 1.3(+1.1 -0.5) dex smaller than that of the optical emission. Viewed as a thin disk…
We present new HST WFPC3 imaging of four gravitationally lensed quasars: MG 0414+0534; RXJ 0911+0551; B 1422+231; WFI J2026-4536. In three of these systems we detect wavelength-dependent microlensing, which we use to place constraints on…
We present estimates for the size and the logarithmic slope of the disk temperature profile of the lensed quasar Q2237+0305, independent of the component velocities. These estimates are based on six epochs of multi-wavelength narrowband…
We review results from our monitoring observations of several lensed quasars performed in the optical, UV, and X-ray bands. Modeling of the multi-wavelength light curves provides constraints on the extent of the optical, UV, and X-ray…
Microlensing of multiply imaged quasars is a unique probe of quasar structure, down to the size of the accretion disc and the central black hole. Flux ratios between close pairs of images of lensed quasars can be used to constrain the…
We have assembled a sample of 37 RLQs that have been imaged with the HST in order to investigate their black hole masses, accretion rates, and the structure of their accretion disks. The black hole masses were estimated from the…
We estimate the accretion rates onto the supermassive black holes that power 20 of the highest-redshift quasars, at z>5.8, including the quasar with the highest redshift known to date -- ULAS J1120 at z=7.09. The analysis is based on the…