Research in Black-Hole Physics and Relativistic Astrophysics

Cornell University, Ithaca NY

Investigators

Abstract

This award supports research in relativity and relativistic astrophysics. A large component of the research is aimed at the numerical solution of Einstein's equations by supercomputer simulations. The proposed research will have a broad impact on our understanding of fundamental physics. The first real tests of general relativity in the strong field regime of black holes are just beginning to occur with experiments like LIGO. To confront theory with observation, one must be able to calculate what the theory predicts. Are the black holes that LIGO observes the black holes predicted by Einstein's theory? The research will have an impact on astronomy. Mergers of binary systems containing neutron stars may lead to the emission of electromagnetic and neutrino signals, as well as gravitational waves. This opens the possibility of concurrently observing such events in multiple ways leading to greater understanding of such events. The simulations will help determine the parameters of such binaries that lead to the strongest electromagnetic and neutrino signals, and the characteristics of these signals (timescale, strength, etc.) that may be important in developing optimal search strategies for detecting these signals. The research will also have an impact on the broader area of computational science. The computational techniques to be developed here can be used to solve problems in many other areas, including fluid dynamics, meteorology, seismology, and astrophysics. Young researchers trained in these techniques are in great demand. Relativity and black holes continue to fascinate the public and allow science to be communicated broadly. Movies of simulations produced by the investigators will continue to provide public outreach. To solve Einstein's equations, the investigators will use a computational technique, pseudospectral collocation, that delivers high accuracy with a much smaller computational cost than other techniques. One focus is to track the coalescence and merger of binary black hole systems and to calculate the gravitational waveform emitted by such processes. A second focus of the research is to study the coalescence and merger of binary systems containing a neutron star and a black hole, or two neutron stars. The investigators will include ever more realistic descriptions of the microphysics in the simulations, such as the equation of state of nuclear matter, neutrino effects, and magnetic fields. The investigators will also develop a new code for computational astrophysics that is designed to take advantage of upcoming exascale machines in a way that current codes cannot. This new code will be based on discontinuous Galerkin methods and task-based parallelism. It will provide transformative capabilities not only for numerical relativity, but for many problems in computational astrophysics.