Related papers: Identifying Lenses with Small-Scale Structure. II.…
Gravitational lens flux ratio anomalies are a powerful probe of small-scale mass structures, often attributed to dark matter subhalos. However, baryonic components can also play a significant role. This study investigates, for the first…
We report the discovery of PSJ2107-1611, a fold-configuration 4.3"-separation quadruply lensed quasar with a bright lensed arc. It was discovered using a convolutional neural network on Pan-STARRS gri images of pre-selected quasar…
Mass clumps in gravitational lens galaxies can perturb lensed images in characteristic ways. Strong lens flux ratios have been used to constrain the amount of dark matter substructure in lens galaxies, and various other observables have…
We study the problem of gravitational lensing by an isothermal elliptical density galaxy in the presence of a tidal perturbation. When the perturbation is fairly strong and oriented near the galaxy's minor axis, the lens can produce image…
We present an analysis of the line-of-sight structure toward a sample of ten strong lensing cluster cores. Structure is traced by groups that are identified spectroscopically in the redshift range, 0.1 $\leq$ z $\leq$ 0.9, and we measure…
Flux ratio anomalies in quasar lenses can be attributed to dark matter substructure surrounding the lensing galaxy and, thus, used to constrain the substructure mass fraction. Previous applications of this approach infer a substructure…
We use a simple statistical test to show that the anomalous flux ratios observed in gravitational lenses are created by gravitational perturbations from substructure rather than propagation effects in the interstellar medium or incomplete…
The magnifications of the images in a strong gravitational lens system are sensitive to small mass clumps in the lens potential; this effect has been used to infer the amount of substructure in galaxy dark matter halos. I study the theory…
We present the first resolved mid-IR (11 micron) observations of the four-image quasar lens H1413+117 using the Michelle camera on Gemini North. All previous observations (optical, near-IR, and radio) of this lens show a "flux anomaly,"…
In Paper I we studied the theory of gravitational microlensing for a planar distribution of point masses. In this second paper, we extend the analysis to a three-dimensional lens distribution. First we study the lensing properties of…
We consider compensated spherical lens models and the caustic surfaces they create in the past light cone. Examination of cusp and crossover angles associated with particular source and lens redshifts gives explicit lensing models that…
X-ray and optical observations of quadruply lensed quasars can provide a microarcsecond probe of the lensed quasar, corresponding to scale sizes of \~10^2-10^4 gravitational radii of the central black hole. This high angular resolution is…
In strong gravitational lensing, the multiple images we see correspond to light rays that leave the source in slightly different directions. If the source emission is anisotropic, the images may differ from conventional lensing predictions…
We explore the origin of flux ratio anomaly in quadruple lens systems. Using a semi-analytic method based on $N$-body simulations, we estimate the effect of possible magnification perturbation caused by subhaloes with a mass scale of <$\sim…
PG 1115+080 is a quadruply lensed quasar at z=1.72 whose image positions are well fit by simple models of the lens galaxy (at z=0.31). At optical wavelengths, the bright close pair of images exhibits a modest flux ratio anomaly (factors of…
Galaxies modeled as singular isothermal ellipsoids with an axis ratio distribution similar to the observed axis ratio distribution of E and S0 galaxies are statistically consistent with both the observed numbers of two-image and four-image…
Lensing flux-ratio anomalies are most likely caused by gravitational lensing by small-scale dark matter structures. These anomalies offer the prospect of testing a fundamental prediction of the cold dark matter (CDM) cosmological model: the…
We present a rigorous, detailed study of the generic, quantitative properties of gravitational microlensing near cusp catastrophes. We derive explicit formulas for the total magnification and centroid of the images created for sources…
Simple models for lensing potentials that successfully reproduce the positions of quadruple images to high accuracy fail abysmally in reproducing the flux ratios of the multiple images, suggesting the presence of small scale structure…
Many gravitationally lensed quasars exhibit flux ratio "anomalies" that cannot be explained under the hypothesis that the lensing potential is smooth on scales smaller than one kpc. Micro-lensing by stars is a natural source of granularity…