Explorations of Non-Supersymmetric Black Holes in Supergravity

Finding a quantum theory of gravity and unifying our description of the fundamental forces in the universe has been a long-standing goal of the physics community for the last several decades. Black holes provide a setting where both gravitational and quantum effects are important, and as such they are valuable in probing how such a theory of quantum gravity must behave; any quantum description of a black hole should be consistent with its macroscopic (low-energy) description in general relativity. The only known examples where the microscopic details of a black hole are understood come from string theory and are heavily reliant on supersymmetry. Little is known about how to extend these descriptions to more realistic, non-supersymmetric settings. In this thesis, we make progress on this front by undergoing a careful exploration of non-supersymmetric black holes in theories of supergravity. In particular, we show how generic Kerr-Newman black holes, when interpreted as solutions to N=2 supergravity, exhibit a surprising amount of universality in their behavior that points to a great deal of simplicity in their underlying quantum description. In the first part of this thesis, we embed arbitrary Kerr-Newman black holes into N=2 supergravity. We then study the quantum fluctuations around these backgrounds and compute their contributions to the black hole entropy. We find that these quantum corrections are protected by a topological quantity and are thus invariant under arbitrary deformations of the black hole away from the BPS limit. The logarithmic corrections to the Bekenstein-Hawking entropy are thus universal and independent of black hole parameters for these black holes. In the second part of this thesis, we study minimal supergravity with higher derivative corrections and show that Kerr-Newman black holes can be consistently embedded into such theories with no modifications required to the geometry. Moreover, we show that these black holes are continuously connected to a BPS geometry. We also find that the entropy of these black holes is a topological invariant and thus insensitive to whether or not the black hole is a BPS state. In the final part of this thesis, we explore the symmetries of off-shell N=2 supergravity and the corresponding constraints these symmetries impose on the theory. In particular, we show that the topological nature of our results follows directly from symplectic duality and supersymmetry. Moreover, these constraints persist even for black hole solutions that break the supersymmetry of the theory. These results establish a previously-unknown level of structure in the underlying microscopic description of these black holes.PHDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/144036/1/amchar_1.pd