Astrophysical Relativity

The main work of this division is on gravitational waves (both data analysis and theoretical modelling of sources) and numerical solutions of Einstein's equations.

Gravitational waves are now becoming a tool for exploring the observable Universe. Kilometer-scale laser-interferometer detectors-LIGO, VIRGO, GEO600, and TAMA300, have been constructed and are rapidly approaching their design sensitivities. LIGO, GEO600, and TAMA300 have already produced scientific data, which has been used to place upper limits on source strengths and event rates. A worldwide network of low-temperature bar detectors also continues to operate and produce scientific data. We expect that the first actual detections will be made in the next few years, ushering in the new field of gravitational wave astronomy. The gravitational wave group in our division is run by Marialessandra Papa. It consists of about twelve members, including staff scientists, computer managers and programmers, postdocs, and grad students. Our gravitational wave (GW) group shares with Cardiff University the main responsibilities for GEO600 data analysis. (The GEO600 project is jointly operated by the AEI's Laser Interferometry and Gravitational Wave Astronomy Division (in Hannover) and the University of Glasgow.) Thanks to a complete data sharing agreement between GEO600 and LIGO, our GW group also plays major roles in LIGO data analyis. In particular, Marialessandra Papa jointly chairs the LIGO Continuous Waves Working Group, and most of our members work with her in searching for continuous gravitational waves from rapidly rotating neutron stars. The GW group has a 360 CPU computer cluster, MERLIN/MORGANE, for computationally intensive data analysis applications and is also deploying searches on the Grid. The GW group also does theoretical work aimed at understanding gravitational-wave sources, as well as work on designing and analyzing advanced GW detector technologies. Additionally, the GW group plays an active role in eLISA, a planned space-based gravitational wave detector. Karsten Danzmann (Director of the AEI Division of Laser Interferometry and Gravitational Wave Astronomy) and Bernard Schutz were among the leaders of the original LISA proposal to ESA in 1993, and the AEI has become a focal point for developing the eLISA mission in Europe.

One of the principal tools for exploring general relativity, including the theory of gravitational wave sources is through numerical simulation on a computer. This is an active area of research worldwide, and a major theme at the Albert Einstein Institute. The numerical relativity group comprises 10-15 scientists and students led by Luciano Rezzolla in the Astrophysical Relativity Division, as well as a number of researchers from the Geometric Analysis and Gravitation Division. A main research focus is the binary black hole problem and the development of numerical hydrodynamics techniques in full general relativity. The group is supported by a local compute cluster, peyote, consisting of 200 dual-processor (Intel) nodes, and 12 TB of disk space.