Strong lensing, plane gravitational waves and transient flashes

Understand

Plane-symmetric gravitational waves are considered as gravitational lenses.

• Numbers of images, frequency shifts, mutual angles, and image distortion parameters are computed exactly in essentially all non-singular plane wave spacetimes.
• For a fixed observation event in a particular plane wave spacetime, the number of images is found to be the same for almost every source.
• This number can be any positive integer, including infinity.