When Nasa released a ‘sonification’ audio during the Black Hole Week the US space agency has been observing, listeners thought for a while it was the soundtrack of some horror movie. While sounds from a black hole are beyond the human audible range, new technology has made it possible to create a wider range of tones so that it can be assumed how it may sound like.
The black hole at the centre of the Perseus galaxy, which is about 240 million light-years away from the earth, has been associated with sound since 2003.
Studies have revealed that pressure waves from the black hole rippled up and down in a heated gas cloud that could be translated into a note. However, the note, some 57 octaves below middle C, is off the human hearing range.
Now, this new sonification, that is black hole sound machine, can produce a wider range of tones.
In this new sonification of Perseus by Nasa, the sound waves astronomers previously identified were extracted and made audible for the first time. In addition to the Perseus galaxy cluster, a new sonification of another famous black hole has been released.
Millions of elusive black holes hide in plain sight — a black hole has such a gravitational pull that even light cannot pass through it, thus making it invisible — across the milky way galaxy, only giving away their presence occasionally through bursts of X-ray light when they feed on stars.
Astronomers have been able to pin down the locations of eight rare pairings of black holes and the stars orbiting them, thanks to the X-ray echoes they release. Previously, there were only two known pairs emitting X-ray echoes in our galaxy.
Black-hole binaries occur when these celestial phenomena are orbited by a star, which they sometimes use to siphon gas and dust as a snack.
How Nasa did it
Nasa converted the echoes into sound waves that just may keep you awake at night.
The research team of the US space agency developed an automated tool dubbed the “Reverberation Machine” to search for echoes from black hole binaries in satellite data.
During the study, the researchers used the Reverberation Machine to look through data collected by NASA’s X-ray telescope called the Neutron star Interior Composition Explorer, or NICER, which is part of the International Space Station.
“We see new signatures of reverberation in eight sources,” first study author Jingyi Wang, a graduate student at the Massachusetts Institute of Technology, said in a statement. “The black holes range in mass from five to 15 times the mass of the sun, and they’re all in binary systems with normal, low-mass, sun-like stars.”
After collecting the eight echoes, the researchers compared them to see how a black hole changes when it releases an outburst of X-rays. A similar portrait emerged for the eight binary systems.
When black holes pull material from an orbiting star, they can launch bright “jets” of particles that go streaming into space at near the speed of light. The research team noticed that during this process, the black hole will release a final, highly energetic flash before it transitions to a low-energy state.
When that last blast occurs, it could mean the black hole’s highly energetic plasma ring (or corona) is releasing energised particles before it disappears. Astronomers can apply this finding to larger supermassive black holes, which function as “engines” at the centre of galaxies and can shoot out particles that can shape galactic formation.
“The role of black holes in galaxy evolution is an outstanding question in modern astrophysics,” study author Erin Kara, assistant professor of physics at MIT, said in a statement. “Interestingly, these black hole binaries appear to be ‘mini’ supermassive black holes, and so by understanding the outbursts in these small, nearby systems, we can understand how similar outbursts in supermassive black holes affect the galaxies in which they reside.”
The echoes of these X-ray emissions can help astronomers map where black holes are located. It’s not unlike echolocation used by bats for navigation. Bats release calls that bounce off obstacles and return as an echo, and the length of the echo’s return helps bats determine the distance of objects.
Black hole echoes are created by two types of X-ray light released from the corona, and astronomers can use the amount of time it takes for the telescope to detect the two types to track how a black hole changes as it gobbles up material from the star.
The black hole echoes aren’t actual sounds we can hear without some help, so Kara collaborated with Kyle Keane, lecturer in MIT’s department of materials science and engineering, and Ian Condry, professor in MIT’s department of anthropology, to turn them into sound waves.
The team tracked changes in the X-ray echoes, determined time lags during transition stages and traced commonalities in the evolution of each black hole outburst. The result sounds like something from a 1950s sci-fi film.
“We’re at the beginnings of being able to use these light echoes to reconstruct the environments closest to the black hole,” Kara said. “Now we’ve shown these echoes are commonly observed, and we’re able to probe connections between a black hole’s disk, jet, and corona in a new way.”
And if you want to hear more spooky black hole sounds, NASA just released a remix of some black hole sonifications for your listening pleasure.