mercredi 27 septembre 2017

Gravitational waves detected in Europe








Advanced Virgo logo.

27 September 2017

The Virgo detector recorded for the first time the phenomenon caused by the fusion of two black holes.

For the first time, gravitational waves were recorded by the European detector Virgo, which was recently put back into service. The observation was jointly with two US instruments, said Wednesday an international scientific team.

The phenomenon has been observed by European and American instruments

"The gravitational waves propagated in space for 1.8 billion years before being detected by the Advanced LIGO detector located in Louisiana (USA), and 8 thousandths of a second later by the one located in the United States. Washington State, and finally six thousandths of a second afterwards by Advanced Virgo located near Pisa in Italy, "the CNRS said in a statement.

The American Ligo (Laser Interferometer Gravitational-Wave Observatory) instrument, made up of two identical detectors in Louisiana and Washington, had already observed this phenomenon three times predicted by Albert Einstein's theory of general relativity in 1915. The very first direct detection, announced on February 11, 2016, was a historic event after 40 years of effort.

But it is "the first detection" for Advanced Virgo, which has been restarted on August 1 after several years of improvements and a few months of tests, explains the National Center for Scientific Research (CNRS). Its arrival in the device allows a much better localization in the sky of the sources of gravitational waves.

Merging two black holes

The waves result from slight perturbations of the space-time frame under the effect of the displacement of a massive object, much like a weight deforms a net. These new waves, detected on August 14, 2017 at 12:30, were produced by the fusion of two black holes, about 1.8 billion light years from Earth.

Virgo Detector

The two monsters, which had masses equal to 25 and 31 times that of the Sun, merged into a single black hole of 53 solar masses, the equivalent of 3 solar masses being converted into energy in the form of gravitational waves.

Weekly Detections

Advanced Virgo is an instrument mainly financed by the CNRS in France and the Istituto Nazionale di Fisica Nucleare (INFN) in Italy. It brings together 250 physicists, engineers and technicians from 20 European laboratories. The international team announced this detection on the sidelines of the G7-science meeting in Turin. Their work will be published in the Physical Review Letters.

Advanced Virgo interferometer, detecting gravitational waves from space

"With the next observations scheduled for the fall of 2018, we can expect such detections every week or even more often," said David Shoemaker, Massachusetts Institute of Technology (MIT) astrophysicist and spokesperson for the Ligo collaboration .

Advanced Virgo - Listening to the cosmic whisper: http://public.virgo-gw.eu/language/en/

Images, Text, Credits: ATS/EGO-Virgo/Orbiter.ch Aerospace/Roland Berga.

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