Perturbative and numerical approach to plasma strong lensing

Using two different approaches, we study imaging in the strong-lensing regime taking into account effects of plasmatic environments on light propagation. First, extend use a perturbative approach that allows us to quickly and analytically calculate position shape images circular source lensed by galaxy. Such an will be compared with obtained from numerical solution lens equations. Secondly, introduce three-dimensional spheroidal model describe spacetime associated dark matter halo around galaxy optical metric incorporate presence plasma medium. The (chromatic) deformation caustic critical curves multiplicity is also analyzed for particular configurations.