Seminarium "Teoria cząstek elementarnych i kosmologia"

Even though, naked singularities are perceived by many scientists only as strictly academic curiosities, solutions of the Einstein equation representing them are not hard to obtain. The well-known Reissner-Nordström (RN) metric is an example that can model black holes as well as naked singularities. It turns out that the RN metric is not only the solution of the Einstein equation coupled to the Maxwell electrodynamics, as it was obtained for the first time more than a century ago, but is also the solution in certain modified theories of gravity.In this talk we will go beyond well-studied accretion onto black holes described by the Kerr metric and investigate the analogous process in the background of the RN one. We will consider both regimes, i.e. when the charge parameter Q is smaller than the mass M of the black hole or when it is greater than M and the metric describes the naked singularity. We will discover new, exciting phenomena like repulsive gravity, levitating atmospheres and much more. Our findings may have applications to astrophysics of the active galactic nuclei (AGNs) with their powerful jets and outflows.