February 2016 – Direct detection of gravitational waves
On September 14, 2015, at 11:50:45 CEST both LIGO detectors registered the same signal, offset by 7 ms. It corresponds to that of two black holes, orbiting each other with increasing velocity, and merging finally. The frequency increases in 0.2 seconds from 35 Hz to 150 Hz, with a maximum signal amplitude of 10-21. The two black holes had 29 and 36 times the mass of our Sun, respectively. The black hole created in the merger has 62 solar masses, meaning that 3 solar masses have been converted into energy in form of gravitational waves.
The increased sensitivity of the LIGO detectors is based on many technologies developed and tested at GEO600: powerful lasers from the Laser Zentrum Hannover and the Albert Einstein Institute in Hannover, monolithic mirror suspensions, and power and signal recycling.
At 16:30 CEST on February 11, 2016, the discovery was announced in press conferences, one of which took place in Hannover.