The background hum of space could reveal hidden black holes

Deep space is not as silent as we have been led to believe. Every few minutes a pair of black holes smash into each other. These cataclysms release ripples in the fabric of spacetime known as gravitational waves. Now Monash University scientists have developed a way to listen in on these events. The gravitational waves from black hole mergers imprint a distinctive whooping sound in the data collected by gravitational-wave detectors. The new technique is expected to reveal the presence of thousands of previously hidden black holes by teasing out their faint whoops from a sea of static.

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Credit: NASA/C. Henze

A visualization of a supercomputer simulation of merging black holes sending out gravitational waves.

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Two black holes of nearly equal mass spiral together and merge, releasing gravitational waves.

In this visualization, orange ripples represent distortions of space-time caused by the rapidly orbiting masses. These distortions spread out and weaken, ultimately becoming gravitational waves (purple). Black spheres represent the black hole event horizons, surfaces beyond which nothing can escape.

The merger timescale depends on the masses of the black holes. For a system containing black holes with about 30 times the sun’s mass, similar to the one detected by LIGO in 2015, the orbital period at the start of the movie is just 65 milliseconds, with the black holes moving at about one-tenth the speed of light.

Space-time distortions radiate away orbital energy and cause the binary to contract quickly. As the two black holes near each other, a new horizon forms around them, creating a single merged black hole that quickly settles into its "ringdown" phase and emits its final gravitational waves.

For the 2015 LIGO detection, these events played out in little more than a quarter of a second. This simulation was performed on the Pleiades supercomputer at NASA's Ames Research Center.

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.

 

I love how that sounds like a heartbeat echo!

Sounds similar to a Doppler recording of a fetus moving around in utero. That's really neat.. notice how nature mirrors around us so much, in the body, in the universe, in nature,( flowers & symmetry). It's fascinating


Glad we have this board