RUI: Numerical Simulations of Black Holes, Neutron Stars and Gravitational Radiation

Bowdoin College, Brunswick ME

Investigators

Abstract

Einstein's theory of general relativity describes all gravitational interactions in the universe, ranging from the force that pulls a falling apple to the Earth, to the expansion of the Universe itself. The equations of general relativity - called Einstein's equations - are sufficiently complex so that they can be solved exactly only under very special circumstances. To understand the merger of two black holes, for example, and to predict the signals that we hope to observe soon with the LIGO gravitational wave observatory, requires computer simulations. This award supports research efforts aimed at developing methods and approaches for such computer simulations. In particular, the focus is on methods that are well suited for the self-consistent treatment of the gravitational forces in supernova explosions. These extremely energetic explosions play an important role in the evolution of the universe, even the development of life, lead to the formation of black holes or neutron stars, and yet we still lack a detailed understanding of the explosion mechanism. The scientific goals of this research effort in numerical relativity include the development and implementation of numerical algorithms for the solution of Einstein's equations of general relativity, as well as their application in the numerical modeling of relativistic objects, in particular neutron stars and black holes. The focus of this work is methods in spherical polar coordinates, which have distinct advantages over Cartesian coordinates for many applications, including gravitational collapse, accretion disks, and supernova calculations. This is done in collaboration with colleagues at the Max-Planck-Institute for Astrophysics in Garching, Germany, on including these methods in relativistic astrophysics simulations with a state-of-the-art treatment of microphysical phenomena. Among the long-term goals are supernova simulations that adopt both these advanced microphysics methods and a self-consistent treatment of relativistic gravitational fields. These results will advance our understanding of these processes and will predict their observational signatures in neutrino, electromagnetic and gravitational wave signals. The latter will be important for the new generation of gravitational wave laser interferometers, including the Laser Interferometer Gravitational wave Observatory (LIGO).