Effective dynamics of black hole horizons

Resumo

In this thesis we present a new aspect pertaining to the effective field theory of general relativity in the limit of a large number D of dimensions. We demonstrate that the theory initially developed to capture the physics of asymptotically flat branes also contains a new family of localized solutions that can be identified with higher dimensional black holes such as the Schwarzschild-Thangerlini or the Myers-Perry black holes in the limit of a large number of spacetime dimensions. Using this tech-nique, we have explored several new aspects of these black hole solutions. We show that the effective large D equations for the asymptotically flat brane also contain an analytic solution that is a gaussian blob (with the same topology as the flat membrane). The blob actually corresponds to a magnification of the geometry near the cap (north-pole) of the black hole. We calculate their (slow) quasi-normal spectrum, which captures the stability of Schwarzschild black holes and also the in-stability of ultraspinning Myers-Perry black holes. Additionally, we find novel class of rotating black bar solutions, that appear as sta-tionary objects in the effective theory since they cannot radiate gravitational waves which are decoupled from the effective theory. We describe a method that allows to construct (Maxwell) charged solutions form every non-charged solution that the large D theory contains. Using this method we construct charged and rotating black holes in the Einstein-Maxwell theory. Furthermore, we explore the solutions that branch of from the (ultra-spinning) My-ers-Perry (MP) black hole and the non-linear extensions of the zero-modes of the analytically known black bar. We study the evolution of higher dimensional black hole collisions by solving numeri-cally the effective equations of motion. We demonstrate that in these collisions it is possible to form black holes with elongated horizons such as black bars and dumb-bells. At high enough angular momentum the black bars and dumbbells can be so elongated that they are susceptible to a Greggory-Laflamme type instability, that leads to the pinch off of the horizon towards a naked singularity. Accordingly, this demonstrates a novel example of a violation of weak cosmic censorship in the quin-tessential process of general relativity: the collision of black holes. Furthermore, we study the evolution and decay of ultraspinning MP black holes and observe remarkably rich structure in the intermediate states of the decay. Lastly, we study how entropy production and irreversibility appear in the large D ef-fective theory. With this tool we study how black hole entropy is generated in sever-al highly dynamical processes, such as the fusion of black holes and the fission of unstable solutions into multiple black holes. We find the black hole fusion is highly irreversible, while fission which follows the decay of unstable black strings generates much less entropy. Additionally, we describe how in processes that contain fusion and fission the intermediate state is quasi-thermalized.