11. February 2022 - 11:30
Sam Dolan (University of Sheffield)
Abstract: In principle, a planar gravitational wave passing through a dense body is focussed at a cusp caustic. For the Sun, the cusp is approximately 550 astronomical units away; for a neutron star the cusp forms close to the crust. Conversely, a planar wave impinging on a black hole will be partially absorbed and scattered, and the black hole's light ring will create characteristic diffraction patterns (orbiting and glories). In this talk I will describe general features of scattering by compact objects, and over-dense regions of the universe. I will draw an analogy with time travel maps for tsunamis, in which the height of the sea bed plays the role of the gravitational potential.