SEMINAR: Supermassive Black Hole Binaries in Galactic Nuclei and Gravitational Wave Emission, simulated on large GPU clusters

Many if not all galaxies contain supermassive black holes (SMBH). We study their growth and evolution by tidal accretion of stars and the presence of a central gas disk, and the motion of central SMBH during and after a galaxy merger. Dynamical Friction and superelastic three-body scatterings with stars will lead to the formation of a SMBH binary - two black holes of millions of solar masses orbiting each other in a distance comparable to the size of our planetary system. Relativistic corrections to Newtonian dynamics (so-called Post-Newtonian approximations) have to be taken into account at this stage, the SMBH binary orbit will have periastron shifts and ultimately lose energy by gravitational radiation emission. Spin-Spin and Spin-Orbit interactions of the SMBH's are taken into account. We show how such a binary emits gravitational radiation across a huge range of the frequency spectrum. Ground based and space based gravitational wave detection is discussed, including pulsar timing, and shows how gravitational wave astronomy will become in the future as rich as electromagnetic astronomy.

If time permits there will be some presentation of the computational science aspect of our work. To use graphical processing units (GPU) for general purpose computations is becoming more and more ubiquitous on all scales - from user's desktops to the most powerful supercomputers. China has been in the past four years pioneering this field, running some very powerful GPU clusters. Our algorithms and their performance and implementation on various GPU cluster architectures, including the recent Kepler hardware, will be shown.