AEI scientist Holger Pletsch awarded one million Euros

May 8th, 2014

New Emmy Noether group for outstanding researcher

Dr. Holger Johannes Pletsch
© Pletsch/AEI

The unusual PSR J1311-3430 pulsar system with the first millisecond pulsar discovered solely by its lighthouse-like gamma-ray emissions (magenta). The record-breaking pulsar system is so compact that it would fit completely inside our Sun. This schematic representation shows the Sun, the companion's orbit, and the companion at its maximum possible size true to scale; the pulsar has been greatly enlarged in contrast.
© SDO/AIA (Sonne), AEI

The astrophysicist Holger Pletsch, leader of an independent research group at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) and the Institute for Gravitational Physics at Leibniz Universität Hannover, develops efficient methods for the discovery of unknown gravitational-wave and gamma-ray pulsars. Starting in April 2014, his excellent research is supported by the Emmy Noether program of the Deutsche Forschungsgemeinschaft (DFG) with a total of one million Euros for a duration of five years.

Fundamental research with pulsars
Pulsars are rapidly rotating neutron stars and play a crucial role in the understanding of several key questions in fundamental physics and astrophysics. “Since the discovery of the first pulsars in the 1960s most known pulsars have been discovered in radio waves,” explains Holger Pletsch. “In 2008 the NASA's Fermi Gamma-ray Space Telescope has opened up a new window onto the universe in the gamma-ray range, providing unique opportunities for pulsar searches and to advance our understanding of neutron stars.”

Fermi has catalogued several hundreds of still unidentified gamma-ray sources, many of which are likely to be pulsars. However finding these hidden treasures represents a tremendous computational challenge. Pletsch is an expert in this field and has already contributed several important breakthroughs.

Innovative and interdisciplinary
In recent years, Pletsch has led the development of new search methods with unprecedented sensitivity. In an interdisciplinary approach he combined techniques from gravitational-wave, gamma-ray and radio astronomy. The novel data analysis methods are highly efficient and very sensitive, and thus facilitate the extremely compute intensive searches for gamma-ray pulsars. In some cases, only those new methods make the discovery of pulsars possible, which previously were completely inaccessible.

Using the volunteer computing system Einstein@Home and the Atlas computer cluster at the AEI, Pletsch's team has already discovered 15 new gamma-ray pulsars – about half of the known gamma-ray-only population. Among them is the current record holder for the pulsar in the tightest orbit with its companion.

“The flexible research grant of the DFG's Emmy Noether program allows us to consequently extend this successful approach,” says Pletsch. “We will refine and also expand our analysis methodologies, which opens up the exciting prospect of discovering completely new pulsar systems.” Pletsch's team cooperates with partners in Germany, France, Poland, and the USA. Their search also employs Einstein@Home, which harnesses idle compute cycles on volunteers' computers from all around the world. More than 360,000 participants put Einstein@Home's aggregated computing power on par with the world's largest supercomputers.

A new era of astronomy
These methods can also be applied to the search for gravitational waves. Gravitational waves are a prediction from Einstein's general theory of relativity, tiny ripples in space time that so far have only been seen indirectly. Following an upgrade, an international network of dedicated detectors will soon start taking data more sensitive than ever before. Their first direct measurements will usher in a new era of astronomy.

The methods developed by Pletsch's team can be used to filter out the faint gravitational-wave signals emitted by rapidly rotating neutron stars – so-called gravitational-wave pulsars – from the long-duration data streams. “Thereby we multiply our scientific returns and are also optimally positioned to make significant contributions to gravitational-wave astronomy in these forthcoming exciting times.”