The Imprint of Small-scale Structure on the Gravitational Lensing by Dark Matter Halos

We explore the signatures of small-scale structures on strong and weak gravitational lensing by dark matter halos. Our lens model consists of a Navarro-Frenk-White halo with an added discrete massive object. Such a model may serve as a starting point for studying the imprint of individual galaxies on the lensing by galaxy clusters, as well as the imprint of satellite galaxies on the lensing by galactic halos. We demonstrate the richness of the critical curves and caustics of the model, and show that the added object may generate caustic structures comparable in size to the original caustics. We study the imprint on the shear pattern and show that the affected region may extend substantially beyond the Einstein radius of the object.