In September 2015, gravitational waves (GWs) were detected for the first time by the LIGO detectors, the two laser interferometers in the United States. It was found that detected GWs originate from the coalescence of two black holes (BHs) in a binary, each weighing about 30 times the mass of the Sun (30 solar mass). Although there have been indirect observations of BHs in the X-ray binaries, their masses are at most 15 solar masses.
With the announcement, on 11 February 2016, of the first detection ever of a gravitational wave by the LIGO and Virgo Collaborations, a New Astronomy, based on listening to the space-time vibrations, was born.
This long-awaited wave, 100 years after the theoretical prediction by Albert Einstein and 50 years after the first experimental efforts, arrived on Earth on 14 September 2015 and was finally perceived by humans with very smart “microphones”.
The new Advanced Virgo interferometer laser beam injection system was switched on on Friday, September 26th 2014 at EGO, the European Gravitational Observatory.
The big interferometers, built to detect gravitational waves for the first time, almost one century after Einstein announced their existence in 1916, are being improved.
On the Earth, there are only four such giant interferometers, with arms up to 4km long: Virgo, near Pisa; GEO600, near Hannover; and the two LIGO interferometers, in Louisiana and Washington State…