AEI scientist Holger Pletsch receives Heinz Maier-Leibnitz Prize

Max Planck scientist awarded most important prize for young scientists in Germany

May 27, 2013

Astrophysicist Holger Pletsch, Independent Research Group Leader at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) and at the Institute for Gravitational Physics of Leibniz Universität Hannover, develops efficient methods to search for unknown neutron stars through their gravitational-wave and gamma-ray emission. For his outstanding work he was awarded the renowned Heinz Maier-Leibniz Prize by the German Research Foundation (DFG) and the Federal Ministry of Education and Research. On June 3, 2013 the prize, valued at €20,000, will be presented in a ceremony in the Magnus-Haus in Berlin.

Einstein's legacy and limited computing power as bottleneck

Almost 100 years ago Albert Einstein formulated his general theory of relativity which revolutionized our understanding of the Universe. Many of the predictions arising from this theory have been experimentally verified with ever-increasing precision; but the direct measurement of one effect, gravitational waves, is still to come. Using these tiny ripples in space-time, astronomers hope to extend our understanding of the cosmos by studying astrophysical objects invisible to today's astronomical methods.

Neutron stars, extremely dense and rapidly rotating remnants of massive stars, are a promising target. They can be discovered by their emission of gravitational waves and gamma-rays. In both cases the available computing power limits the sensitivity of the search. Together with AEI colleagues, Holger Pletsch develops new and highly-efficient analysis methods. He was awarded the Heinz Maier-Leibnitz Prize for his pioneering work in this area.

Efficient methods for gravitational-wave data analysis

Besides building more sensitive detectors, data analysis methods play an essential role in the direct detection of gravitational waves. This is because observational data from existing detectors are dominated by noise sources and hunting for signals requires an enormous computational effort. This is the case in the search for gravitational waves from rapidly rotating neutron stars.

Optimizing this kind of search to make the best use of the computer power is one subject of Holger Pletsch's research. The newly-developed data analysis methods extend the spatial volume to which the search is sensitive by a factor of about 200. The probability of detecting gravitational waves from rapidly rotating neutron stars is increased by the same factor. This significantly increases the hope of making the first direct measurement of gravitational waves.

New gamma-ray pulsar discoveries via technology transfer

Pletsch also transferred these methods to the physically and mathematically related search for socalled gamma-ray pulsars, and discovered almost a dozen of these objects within a short period of time. Pulsars are rotating neutron stars acting as cosmic beacons. They emit gamma-ray photons in a lighthouse-like beam which is swept through space by the rotation of the stellar remnant. The difficulty in finding a gamma-ray pulsar in a so-called blind search is that a priori none of the parameters characterizing the pulsar is exactly known. Testing for all possible parameter combinations in data sets spanning multiple years and thereby discovering a periodic signal requires an enormous computational effort.

Holger Pletsch modified and extended the methods initially developed for gravitational-wave data analysis and used them for the search for unknown gamma-ray pulsars. These improved and more efficient methods for the first time enabled the search over a larger parameter space with higher sensitivity than before. In collaboration with colleagues form the Max Planck Institute for Radio Astronomy in Bonn, Pletsch discovered eleven new gamma-ray pulsars in data from the Fermi satellite. This is more than a third of the pulsars found previously with conventional methods. The discoveries include many unusual pulsars, which have opened ways to further original research.

Background information:

Internationally awarded scientist

After studying physics at the TU Kaiserslautern and at the University of Wisconsin-Milwaukee, Holger Pletsch did his doctoral studies at the AEI and obtained a PhD with highest praise from Leibniz Universität Hannover in 2009. His dissertation was awarded two prizes. As youngest PhD student with an excellent degree in 2009, the Max Planck society awarded Holger Pletsch the Dieter-Rampacher Prize. In the same year the Gravitational Wave International Committee (GWIC) awarded him the international GWIC-Thesis Prize for the best dissertation in the field of gravitational-wave astronomy. Since 2013 he has been working as an Independent Research Group Leader at the AEI.

Neutron stars as instruments of fundamental research

Neutron stars provide astronomers with laboratories for testing fundamental physics in extreme conditions. Because of their strong gravitational field they are ideal test beds for Einstein's general theory of relativity. Their high density allows scientists to study matter in conditions not attainable in laboratories on Earth. As remnants of exploded stars they shed light on their unusual “paths of life” and deepen our understanding of stellar evolution. Neutron stars also are considered a promising source for gravitational waves, whose direct detection will usher in a new era of astronomy.

The Heinz Maier-Leibnitz Prize

The Heinz Maier-Leibnitz Prize is named after a former president of the DFG and has been awarded annually to young scientists since 1977. The DFG views the prize as a distinction for the young researchers' outstanding achievements, which should assist them in furthering their scientific careers. The Federal Ministry of Education and Research provides the prize money. On June 3, 2013 the prize, valued at €20,000 is presented in a ceremony at the Magnus-Haus in Berlin.

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