Gravitational waves sent out from a pair of colliding black holes have been converted to sound waves, as heard in this animation. On September 14, 2015, LIGO observed gravitational waves from the merger of two black holes, each about 30 times the mass of our sun. The incredibly powerful event, which released 50 times more energy than all the stars in the observable universe, lasted only fractions of a second.
In the first two runs of the animation, the sound-wave frequencies exactly match the frequencies of the gravitational waves. The second two runs of the animation play the sounds again at higher frequencies that better fit the human hearing range. The animation ends by playing the original frequencies again twice.
As the black holes spiral closer and closer in together, the frequency of the gravitational waves increases. Scientists call these sounds "chirps," because some events that generate gravitation waves would sound like a bird's chirp.
Audio Credit: Caltech/MIT/LIGO Lab
Since 2007, the data from the LIGO, GEO and Virgo detectors are shared and analyzed together as from a single "telescope". Sharing the data is of main importance to reject local perturbations in the data and to localise the gravitational wave in the sky, i.e. to make astronomy.
Credits: Virgo Collaboration/LAPP and Tom Patterson (www.shadedrelief.com)