Gravitational waves caught again

'The second detection of the gravitational waves from merging black holes is very important. The foundation for the gravitational-wave astronomy is becoming stronger and more reliable,' says Valery Mitrofanov, Professor of the Physics Department of the Moscow State University. Studies are conducted within the LIGO Scientific Collaboration (LSC) -- a team of more than 1,000 scientists from the United States and 14 other countries, including Russia. Among the Russian scientists of the LIGO Collaboration is also the staff of the Physics Department of the Moscow State University: Head of the Moscow group, professor of physics of oscillations, Valery Mitrofanov, professors of the Faculty of Physics, Igor Bilenko, Sergei Vjatchanin, Mikhail Gorodetsky, Farid Khalili, Sergei Strygin, assistant Leonid Prokhorov. The development of the detectors and the data analysis involve more than 90 universities and research institutes. About 250 student participants also contribute significantly. LSC detectors network includes LIGO interferometers and the GEO600 detector.

'It is important that the second signal has been generated by the black holes with the relatively small masses, which better corresponds the astrophysicists' predictions. Now we can be more confident that the first event was not a rare exception,' reports Farid Khalili, Professor of the Faculty of Physics of the Moscow State University.

'Gravitational waves, these flying pieces of space-time curvature, from something exotic became a common source of the new information about the universe and opened the era of gravitational astronomy,' describes the situation Sergey Vjatchanin, Professor of the Physics Department of the Moscow State University.

In contrast to the signal recorded on the first detection of gravitational waves, which was clearly visible with the noise on its background, the second signal was weaker and not clear in the noise. However, the scientists were able to 'filter' it with the help of a special technique.

Physicists have come to the conclusion that the observed gravity waves were generated by the two black holes of 14 and 8 solar masses in the last fraction of a second before they merged to form a single, more massive rotating black hole of 21 Solar masses.

During the merger which occurred about 1.4 billion years ago the amount of the energy equivalent to roughly one solar mass has become a gravitational wave. The recorded signal was produced on the last 27 turns of black holes before they merge. The detector in Livingstone recorded the event 1.1 milliseconds before the detector in Hanford, which allows to give a rough estimate of the location of the source on the celestial sphere.

The first detection of gravitational waves, announced February 11, 2016, was a milestone in the development of physics. It confirmed the prediction of the general relativitytheory that Albert Einstein made in 1915, and marked the beginning of the new field of gravitational-wave astronomy. Detection of the two signals within four months of the first Advanced LIGO observations cycle allows predicting how often the signals of the gravitational waves may be detected in the future. Both discoveries were made possible thanks to the more refined Advanced LIGO detectors, which are more sensitive than the first generation of the LIGO detectors and can significantly increase the amount of the probed the universe. The next cycle of observations is scheduled for autumn this year. It is expected that by that time further improvement of the LIGO detectors' sensitivity will be able to enlarge the volume of the probed Universe 1,5 - 2 times. It is also expected that in the second half of this observation cycle the Virgo detector will become operational.

'The new result marks the conversion of LIGO from an extremely expensive scientific experiment into the instrument for the continuous extraction of the otherwise unavailable information about the structure of the Universe,' says Mikhail Gorodetsky, professor of the Physics Department of the Lomonosov Moscow State University. 'The repeating detection of gravitational waves gives a powerful impetus for the creation of a new generation of gravitational wave detectors for the further study of the Universe all over the world,' concludes Sergei Strygin, Associate Professor of the Physics Department of MSU.

Source: Lomonosov Moscow State University