This Time With A Very Special Twist: Third Gravitational Wave Signal Observed

Researchers from the LIGO Scientific Collaboration (LSC) have once again been able to prove the existence of gravitational waves, thereby fortifying this new area of astronomy. In the most recent issue of Physical Review Letters, the first of these is the first clues. Prof. Dr. Roman Schnabel from the Institute of Laser Physics and the Center for Optical Quantum Technologies at the University of Hamburg heads the working group in the research project.

Scientists from the LIGO-Virgo Collaboration (LVC) have once again demonstrated gravitational waves, thus permanently strengthezning this new field of astronomy. The new edition of the journal "Physical Review Letters" also shows that for the first time indications of how the black holes involved in the formation of the waves turn are being discovered. The University of Hamburg is associated with the working group of Prof. Dr. Roman Schnabel from the Institute of Laser Physics and the Center for Optical Quantum Technology.

A collision of two black holes and the resulting gravitational waves were detected in January 2017 for the third time after September and December 2015. In the current case, which is called GW170104, the two black holes were about three billion light years away - the furthest distance of all previous proofs. The new black hole has 49 times the mass of the sun, a solar mass corresponding to 1.99 quadrillion or 332,946 earth masses.

The case, which has now been proved, also provides for the first time indications of how the two black holes, which then later collapsed and generated the gravitational waves. Two black holes must circle each other, but not just that - as a rule each one rotates around its own axis. Sometimes these two directions coincide (directed spin), but they can also rotate counter-clockwise. How the two black holes have turned exactly in the current case is not apparent from the data, but there is evidence that at least one of the black holes has turned counter to the overall motion of the structure. Further investigations on this question could also reveal how such a pair at all resembles.

Since spring 2015, the University of Hamburg has been a member of the LIGO Scientific Collaboration (LSC) and the GEO Collaboration, which operates the German-British gravitational wave detector GEO600. The physicist himself has been a member of the GEO Collaboration since 2003, has been a member of the LSC since 2005, and has been the chairman of the LSC working group "Quantum Sounds" since 2013. He is working with the team at the University of Hamburg to improve the measurement sensitivity of gravitational wave detectors. During his work at the Leibniz University of Hanover, Prof. Schnabel developed the world's first source of light with a so-called "squashed quantum noise", with the aid of which the precision in measurements can be significantly increased.

Gravitational waves provide fundamental information about the origin and nature of gravitation. In September 2015, the researchers were able to observe the mysterious waves in space by means of the four-kilometer detectors of the "Laser Interferometer Gravitational Wave Observatory" (LIGO) in Livingston and Hanford in the USA. Albert Einstein had predicted the existence of gravitational waves in 1916 on the basis of his general relativity theory. Their direct observation therefore allows a new view of the universe, as up to now, the knowledge about the universe has been based on measurements of electromagnetic waves, Eg light or gamma radiation.

LIGO is financed by the National Science Foundation (NSF) and operated by MIT and Caltech. Facilities from Germany (Max Planck Society), the UK (Science and Technology Facilities Council) and Australia (Australian Research Council) have also made significant contributions to the project. In total, more than 1000 scientists from all over the world work in the LIGO Scientific Collaboration, which includes the GEO collaboration. LIGO also cooperates with "Virgo", a consortium of 280 European researchers located in the European Gravitational Observatory near Pisa, and the Center National de la Recherche Scientifique (CNRS), the Istituto Nazionale di Fisica Nucleare ( INFN) and the Nikhef Research Center.