Two families of astrophysical diverging lens models

Understand

In the standard gravitational lensing scenario, rays from a background source are bent in the direction of a foreground lensing mass distribution.

• Diverging lens behaviour produces deflections in the opposite sense to gravitational lensing, and is also of astrophysical interest.
• In fact, diverging lensing due to compact distributions of plasma has been proposed as an explanation for the extreme scattering events (ESEs) that produce frequency-dependent dimming of extra-galactic radio sources, and may also be related to the refractive radio-wave phenomena observed to affect the flux density of pulsars.
• In this work we study the behaviour of two families of astrophysical diverging lenses in the geometric optics limit, the power-law and the exponential plasma lenses.