Abstract

Contributed Talk - Splinter Relativistic   (MW-2050)

Photon rings and shadows of Kerr black holes immersed in a swirling universe

Rogério Capobianco, Betti Hartmann, Nikhita Vas, Jutta Kunz, João Novo
University of Sao Paulo, University of Oldenburg, University College London, University of Aveiro

We discuss photon rings around as well as shadows of Kerr black holes immersed in a swirling spacetime (KBHSU). We find that the spin-spin interaction between the angular momentum of the black hole and the swirling of the background leads to new interesting effects as it breaks the symmetry between the upper and lower hemispheres. We find that a pair of light rings with different radii exists for all values of the parameter space. As the value of the swirling parameter is increased at fixed angular momentum of the black hole the two disconnected patches of the ergoregions eventually merge. The light ring at this merger possesses no angular velocity (as measured by an observer at infinity) and is called a light point. To our knowledge, this is the first time the existence of such a light point in a black hole space-time is reported.