Gravitation and Black Holes: From Magnetospheres to Firewalls

University Of Maryland, College Park, College Park MD

Investigators

Abstract

This research is directed at developing an improved understanding in three different areas of gravitational physics: 1) puzzling issues that arise when applying quantum mechanics to black holes, 2) tests of possible deviations from standard relativity theory, 3) theory of strong magnetic fields around astrophysical black holes and in other systems. On the second topic, one project involves calculating the predicted form of gravitational waves from spherical collapsing stars and supernovae in a modified gravity theory. Another is a study of the viability of such a theory in the quantum realm, and a third is to develop alternative but similar approaches to quantum gravity. Topics in the third category include the nature of astrophysical jets, and energy extraction from black holes and stars spinning or moving in a magnetized cloud of charged particles. Also, this work studies the impact of gravity on the generation and properties of twisted magnetic field lines, and the mathematical structure of the basic equations and their simulation on computers. All of these approaches address fundamental questions regarding the structure of the universe. The corresponding results will be disseminated through written articles, as well as seminars, conference talks, colloquia and lecture series. The PI will provide instruction and mentoring to a postdoctoral scholar, as well as graduate and undergraduate students, regarding scientific research, writing, and verbal communication. The PI will seek out opportunities to speak on this topic to audiences ranging across the spectrum from the general public to specialists in gravitational physics. In the quantum gravity realm, one project concerns the black hole information paradox and the possible role of the Wheeler-de Witt equation in resolving it. Specifically, this work studies the redundant encoding of information into the local degrees of freedom described by a wave function satisfying the Wheeler-de Witt equation. Another project involves the relation of black hole entropy to vacuum entanglement and Noether charge. This research will try to determine whether the entropy contribution from non minimal coupling is balanced by a corresponding entanglement entropy change in adiabatic physical processes involving matter crossing black hole horizons. On the Lorentz violating gravity topic, this project studies whether the proposal for a UV complete, "Lifshitz" quantum gravity can pass the stability test, when all the higher derivative terms are taken into account at the non-linear level. We will also examine whether the idea of Lifshitz scaling can be applied in a spacetime with a preferred temporal threading but no preferred spatial foliation. Finally, the magnetosphere topics are will concentrate on the definition, computation and interpretation of magnetic helicity in a general relativistic setting, and in the presence of boundaries such as the surface of a neutron star or the horizon of a black hole. This should be useful in determining the role of helicity injection and conservation, and how it relates to energy minimization, in a general relativistic setting.