# Brain Gain: Professor Harald Pfeiffer joins the Max Planck Institute for Gravitational Physics as group leader.

The world-renowned expert for numerical simulations of black holes returns to Germany from Canada.

Starting August 1^{st}, 2017, Dr. Pfeiffer will lead a research group on “Numerical Relativity” in Professor Alessandra Buonanno’s department at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) in Potsdam. The group will solve Einstein’s field equations on powerful computer clusters to understand the mergers of binary black holes and/or neutron stars, which are the sources of the strongest gravitational waves for LIGO.

“I am very pleased that Harald Pfeiffer is joining the AEI,” says Alessandra Buonanno, Director of the Astrophysical and Cosmological Relativity division. “He is a world-class expert in numerical simulations of binary black holes, and we have successfully been collaborating for many years. His expertise is just what the division needs now, as we move forward in the new era of gravitational-wave physics and astrophysics after the first observations of binary black holes by LIGO.

“Numerical-relativity simulations are indispensable for building very accurate waveform models,” says Professor Buonanno. “They augment the analytical-relativity methods we also use, so that we can produce a very large number of approximate solutions of the Einstein equation in a very short time. Those waveform models are then employed in LIGO to search for signals, unveil the astrophysical properties of the sources, and test Einstein’s theory of General Relativity.

“I'm excited to be coming to the AEI,” says Professor Pfeiffer. “At the institute I find optimal conditions for my research – a stimulating atmosphere and a high-end computer infrastructure. I am deeply impressed by the breadth of expertise at the institute, and I am looking forward to new and productive collaborations within the Institute.” The division of Astrophysical and Cosmological Relativity runs Minerva, a brand-new 10,000 core high-performance computer cluster, which Pfeiffer will use for numerical simulations.