Research in Black-Hole Physics and Relativistic Astrophysics

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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. One focus is to track the coalescence and merger of binary black hole systems and to calculate the gravitational waveform emitted by such processes. These processes are primary targets for gravitational wave detectors now being deployed, like LIGO, and there is an urgent need for reliable waveforms. The investigators will use a computational technique, pseudospectral collocation, that delivers high accuracy with a much smaller computational cost than other techniques.Other applications will include benchmarking of analytical approximations, such as the post-Newtonian and Effective One Body techniques; computations in difficult regimes of parameter space such as high spins and mass ratios; and analytical explorations of the numerical spacetimes to improve our understanding of strong field gravity. 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. These are also prime scientific targets for LIGO. 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.This research will have a broad impact on our understanding of fundamental physics. There are currently no real tests of general relativity in the strong field regime of black holes. For experiments like LIGO to confront theory with observation, one must be able to calculate what the theory predicts. Are the black holes that LIGO may observe the black holes predicted by Einstein's theory? The research will have an impact on astronomy. Mergers of compact binaries containing neutron stars may lead to the emission of electromagnetic and neutrino signals, opening the possibility of concurrently observing such events in multiple ways leading to greater understanding of such events. Simulations carried out by this project will help determine what signals to look for and how to interpret them when they are detected. 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.