In space you do not hear the scream of a black hole, but you clearly hear its song.
In 2003, astrophysicists working with the Chandra X-ray Observatory in orbit around NASA discovered a pattern of waves in X-rays of giant clusters of Perseus constellation galaxies. These were pressure waves – or sound waves – 30,000 light-years in diameter and thin, ultra-hot gas radiating from outside, filling the clusters of galaxies. They were caused by periodic explosions from a supermassive black hole in the center of a cluster 250 million light-years from us that contains thousands of galaxies.
During the oscillation period of 10 million years, the sound waves were acoustically equivalent below the 57 octave of the B-plane in the middle of C, the tone that the black hole has apparently occupied for the last two billion years. Astronomers suggest that these waves act as a brake on star formation and keep the gas in the cluster too hot to condense into new stars.
Chandra astronomers recently “waved” these waves, at signaling speeds of 57 or 58 octaves at their original height, quadrillion times their frequency so that it could be heard by the human ear. As a result, the rest of us now hear the song of intergalactic sirens.
Through these new space headphones, Perseus’s black hole echoes the horrible sighs and grunts of this listener with the astonishing tones of an alien radio signal that Jody Foster hears through headphones in the sci-fi movie Contact.
As part of an ongoing project to “sonify” the universe, NASA has also released similar generated sounds in a dazzling node energy cannon fired from a giant black hole in the center of a large galaxy known as M87. These sounds reach us 53.5 million light-years away as a brilliant sequence of orchestral tones.
Another sonic project was carried out by a group led by Erin Cara, an astrophysicist at the Massachusetts Institute of Technology, as part of using an echo of X-ray light to draw the environment around black holes as well as bats. A voice to catch mosquitoes.
It’s the result of Black Hole Week, NASA’s annual social media extravaganza, May 2-6. As it happens this week, big news is set for May 12, when researchers with the Event Horizon Telescope, which created the first image of a black hole in 2019, have to announce their latest results.
Black holes, as stated by Einstein’s general theory of relativity, are objects with such strong gravity that nothing can escape, not even light, let alone sound. Paradoxically, they can also be the brightest objects in the world. Before any matter can disappear into a black hole forever, theorists suggest that the gravitational field of the hole accelerates to the speed of light and heats up, rotating millions of degrees. This would cause X-rays to flicker, generate interstellar shock waves, and compress high-energy cannons and particles into space, like so many toothpastes from a tube.
In one common scenario, a black hole exists in a binary system with a star and steals material from it, which accumulates in a dense, clear disk – a visible donut – that sporadically generates X-ray radiation.
Using data from a NASA instrument called the Neutron Star Interior Composition Explorer (NICER), a team led by Jingyi Wang, an MIT graduate student, searched for an echo or reflection of these X-ray bursts. The time lag between the original X-ray blasts and their responses and distortions caused by their proximity to the strange gravity of black holes has suggested the evolution of these violent explosions.
Meanwhile, Dr. Cara was working with education and music experts to turn the X-ray reflection into an audio sound. In some simulations of this process, he says, flashes move around a black hole, reflecting a change in their wavelength ratio.
“I just love that we can ‘hear’ in these simulations of general relativity,” Dr. Karam said in an email.
Eat Your Heart, Pink Floyd.