In space you can’t hear a black hole screaming, but obviously you can hear it singing.
In 2003, astronomers working with NASA’s Lunar X-ray Observatory discovered a pattern of waves in the X-ray glow of a large cluster of constellations in the constellation Perseus. These were pressure waves – that is, sound waves – transmitted around 30,000 light-years and outward by the thin, ultrahot gas that entangled the galaxy clusters. They were caused by periodic explosions from a supermassive black hole at the center of the cluster, 250 million light-years away and containing thousands of galaxies.
With an oscillation period of 10 million years, sound waves sound waves were equivalent to B-flat 57 octaves below central C, a tone that has apparently had black holes for the last two billion years. Astronomers suspect that these waves act as a break on star formation, keeping the gas in the cluster too hot to condense into new stars.
Lunar astronomers have recently “sonified” these waves by accelerating the signals from their original pitch to 57 or 58 octaves, and increasing their frequency quadrillion times so that the human ear can hear them. As a result, the rest of us can now hear intergalactic sirens singing.
Through these new cosmic headphones, the Perseus Black Hole is creepy and thunderous which reminds the listener of the glaming tones marking the alien radio signal that the pair hears through the headphones in the Foster science fiction film “Contact”.
As part of an ongoing project to “sonify” the universe, NASA also released similarly generated sounds of bright knots in a jet of energy shooting from a huge black hole in the center of a giant galaxy called the M87. These sounds reach us in 53.5 million light-years as a glorious succession of orchestral tones.
As part of an effort to use light echoes from X-ray explosions to map the environment around a black hole, another sonication project, such as a bat, has been carried out by a group led by Erin Cara, an astrophysicist at the Massachusetts Institute of Technology. The sound of mosquitoes catching.
This is the culmination of “Black Hole Week”, NASA’s annual Social Media Extravaganza, May 2-6. As it happens this week, May 12 provides the big news prologue, while researchers with the Event Horizon Telescope, who created the first image of a black hole in 2019, are due to announce their latest results.
Black holes, as determined by Einstein’s general theory of relativity, gravitational objects are so strong that nothing, not even light, very little noise, can escape. Paradoxically, they may be the brightest things in the universe. Before any kind of object disappears forever into a black hole, theorists believe that it will accelerate through the gravitational field of the hole at the speed of near light and heat up to millions of degrees. This X-ray will spark flashes, generate interstellar shock waves and squeeze high-energy jets and particles from the tube into a lot of toothpaste-like space.
In a typical scenario, a black hole exists with stars in a binary system and steals content from them, which transforms into a dense, bright disk – a visible donut of doom – that produces scattered X-ray outbursts.
Using data from a NASA instrument called the Neutron Star Interior Composition Explorer (NICER), a group led by MIT graduate student Jingyi Wang explored the echoes or reflections of these X-ray explosions. Due to the proximity of the original X-ray explosions and the strange gravity of the black holes, the time delay between their echoes and distortions gives an insight into the evolution of these violent explosions.
Meanwhile, Dr. Cara is working with education and music experts to convert X-ray reflections into audible sounds. In some simulations of this process, she said, the flash goes all the way around the black hole, causing a tailtail shift in their wavelength before being reflected.
“I like that we can ‘hear’ general relativity in this simulation,” said Dr. Cara said in an email.
Pink Floyd, get your heart out.