Numerical Relativity Framework for Strong-Field Tests of Gravity

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

General relativity and quantum physics have revolutionized science in the last century, and laid the foundations for every-day gadgets from the GPS systems to the microchips in our mobile phones. Yet, a consistent theory of quantum gravity has remained elusive. The quest for a such a "theory of everything" typically yields extensions of general relativity that impact the strong gravity regime unfolding during the collision of black holes and neutron stars. LIGO's Nobel-prize winning discoveries of gravitational waves emitted during their inspiral and merger have opened new discovery channels to probe the very nature of gravity. The key objective of this award is to enable new observational tests of gravity in its most extreme, nonlinear regime and thus promote the progress of science of NSF's "Windows on the Universe" Big Idea. The research will be integrated with the creation of an annual, international "Gravitational Wave Day." This series of broader impact activities aims at promoting the latest discovery in Gravity and Gravitational Wave physics to the general public as well as high-school students. This award supports the mathematical and computational development of well-posed time evolution formulations of beyond-GR theories, beyond the weak field approximation, for numerical relativity. The derivation will adapt recent results in viscous hydrodynamics and relativity for the four-dimensional theory, which will be cast as a Cauchy problem with a BSSN or Z4 type reformulation and using an adapted moving puncture gauge. The award furthermore supports the implementation in the PI's end-to-end, open-source numerical relativity framework Canuda. It is designed highly modular and, thus, adaptable to a large class of theories to enable the largest possible discovery space. The second part of the award focuses on extensive simulations of compact binaries in quadratic gravity, the investigation of their nonlinear dynamics, including new effects like dynamical (de-) scalarization, and the construction of numerical gravitational waveforms in quadratic gravity. 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.