Theoretical Studies in Gravitation and Astrophysics

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

This award supports research in relativity and relativistic astrophysics, and it addresses the priority areas of NSF's "Windows on the Universe" Big Idea. The detection by LIGO/Virgo Scientific Collaboration of gravitational wave (GW) events from binary black hole (BHBH) mergers, binary neutron star (NSNS) mergers and several likely black hole-neutron star (BHNS) mergers opened a new window in the Universe that can help us understand the physics of matter under the most extreme conditions, something impossible by traditional means. The combined detection of GW, electromagnetic (EM) as well as neutrino radiation promises to resolve a number of long-standing astrophysical puzzles, such as the origin of short gamma-ray bursts (sGRBs) and r-process elements, as well as the nature of matter at supranuclear densities. Multimessenger astrophysics requires a comprehensive understanding of the physics of compact objects in a variety of configurations. The project will address several different problems whose common feature is the behavior of matter under extreme conditions in a dynamical, strongly gravitating regime and will involve General Relativity, relativistic hydrodynamics and magnetohydrodynamics, as well as EM and neutrino transport. Most of these topics represent long-standing, fundamental problems in theoretical physics requiring large-scale computation for a solution. Hence this program involves a significant degree of large-scale simulations on supercomputers, in addition to analytical modeling. Movies of the simulations produced by the PIs will continue to be used as an undergraduate training vehicle. The research and outreach activities supported by this grant help promote the use of computers and visualization tools at all levels of education, as well as public awareness of some the latest and most exciting developments in gravitational physics and astrophysics. Young researchers trained in these areas will acquire skills that are useful beyond the scope of astrophysics in a plethora of applied domains, and hence they will be in great demand. To understand the current and future observations and, in particular, the interplay between strong gravity, EM, and the underlying microphysics, it is crucial to compare them to predictions from theoretical modeling. The problems to be tackled comprise both initial value and evolution computations and will treat spacetimes containing black holes immersed in gaseous environments, as well as spacetimes containing neutron stars with magnetic fields and both EM and neutrino radiation. Some of the topics for investigation include the inspiral and coalescence of compact binaries (BHBHs, NSNSs and BHNSs); the generation of GWs from merging binaries and other promising astrophysical sources, and their counterpart EM signals; gravitational collapse; the stability of magnetized rotating, relativistic stars and the evolution and final fate of unstable stars; gamma-ray burst sources; the formation and growth of supermassive black holes (SMBHs) from the magnetorotational collapse of supermassive stars and other scenarios; circumbinary disks around merging binary SMBHs in the cores of galaxies and quasars; and the profiles and observable signatures of dark matter around SMBHs in galaxy cores, including the Milky Way, and the dynamical evolution of clusters containing dark matter, stars and SMBHs. The results have important implications for astronomical observations, including those collected by and/or planned for GW interferometers. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.