Relativistic Gravitation and Astrophysics

Washington University, Saint Louis MO

Investigators

Abstract

The detection of gravitational waves from astrophysical sources will open a new window for astronomy and provide new tests of Einstein's theory of general relativity. Interpreting the observations and advancing this new field will require accurate theoretical gravitational waveforms calculated from the theory. This project will contribute to providing the needed waveforms, by solving Einstein's equations systematically in a "post-Newtonian", or slow-motion, weak-field approximation to general relativity. Using this method it will be possible to study the effects of the interior structure of the bodies and the effects of spin on the motion and gravitational waveform, to high order in the post-Newtonian (PN) expansion. PN methods will also be used to calculate the recoil velocity experienced by black holes formed from an inspiral and merger of spinning compact objects, and to estimate the total energy and angular momentum radiated during the inspiral and plunge. A novel diagnostic tool, based on higher-order PN methods, will be further developed to elucidate the physical content of numerical simulations of black-hole and neutron-star binary inspiral. Ways to use gravitational-wave data to test alternative theories of gravity in new regimes and to measure astrophysical parameters will also be studied. The possibility of testing general relativity in the vicinity of the massive black hole in the center of our galaxy using future adaptive optics infrared telescopes will be analysed by studying orbital perturbations of stars in close orbits near the hole. Education and training of graduate and undergraduate students will be integrated into the research program. A post-doctoral researcher will also receive additional education and training under the grant. The PI will continue to give public lectures on topics related to this research, bringing understanding of the validity and implications of Einstein's ideas to the broader community. He will continue to update his comprehensive review article on experimental gravitation for the web-based journal Living Reviews in Relativity, and will continue to develop his website with web pages providing information on general relativity and its empirical foundation. The work on equations of motion, gravitational waveforms and analysis of gravitational-wave data will impact the field of astronomy, as gravitation-wave observations, which rely upon these calculations, become a reality. The work on recoil velocities may impact astrophysical modelling of the growth of massive black holes in galaxies. The research on the post-Newtonian diagnostic will foster closer ties between the PN experts and numerical relativity experts, leading to more realistic simulations of the important final phase of binary inspiral.