Hear the strange sounds of a singing black hole
In space you can’t hear the scream of a black hole, but apparently you can hear it sing.
In 2003, astrophysicists worked with NASA’s Chandra X-ray Observatory in orbit detected a pattern of ripples in the X-ray glow of a gigantic cluster of galaxies in the constellation of Perseus. They were pressure waves – that is, sound waves – 30,000 light-years wide and radiating outward through the thin, ultra-hot gas that pervades clusters of galaxies. They were caused by periodic explosions from a supermassive black hole at the center of the cluster, which is 250 million light years away and contains thousands of galaxies.
With an oscillation period of 10 million years, the sound waves were acoustically equivalent to a B flat 57 octaves below middle C, a tone the black hole has apparently maintained for the past two billion years. Astronomers suspect that these waves act as a brake on star formation, keeping the gas in the cluster too hot to condense into new stars.
Chandra astronomers recently “sonified” these ripples by accelerating signals 57 or 58 octaves above their original pitch, increasing their frequency quadrillion times to make them audible to the human ear. As a result, the rest of us can now hear the intergalactic siren song.
Through these new cosmic headphones, the black hole of Perseus it makes eerie moans and rumbles which reminded this listener of the galumph tones that mark an alien radio signal that Jodie Foster hears through headphones in the science fiction film “Contact”.
As part of an ongoing project to “sonify” the universe, NASA has also released a similar generation sounds of light knots in a jet of energy firing from a giant black hole in the center of the huge galaxy known as M87. These sounds reach us across 53.5 million light years as a majestic succession of orchestral tones.
Another sonification project was undertaken by a group led by Erin Kara, an astrophysicist at the Massachusetts Institute of Technology, as part of an effort to use the light echoes of X-ray bursts to map the environment around black holes. just as they use sound bats to catch mosquitoes.
This is all a consequence of “Black Hole Week,” in an annual NASA social media extravaganza, May 2-6. As happens this week, a prelude to big news on May 12, when researchers with the Event Horizon Telescope, produced in 2019 the first image of a black holethey will announce their latest results.
Black holes, as decreed by Einstein’s theory of general relativity, are objects with such strong gravity that nothing, not even light, much less sound, can escape. Paradoxically, they can also be the brightest things in the universe. Before any kind of matter disappears forever in a black hole, theorists speculate, it would be accelerated to near-light speeds by the hole’s gravitational field and heated, swirling, to millions of degrees. This would trigger X-ray bursts, generate interstellar shockwaves, and squeeze high-energy jets and particles through space like much toothpaste from a tube.
In a common scenario, a black hole exists in a binary system with a star and steals material from it, which accumulates into a dense, bright disk – a visible donut of doom – that produces sporadic bursts of X-rays.
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 echoes or reflections from these X-ray bursts. The original Xs and their echoes and distortions caused by their proximity to the strange gravity of black holes offered insight into the evolution of these violent outbursts.
Meanwhile, Dr. Kara worked with education and music experts to convert X-ray reflections into audible sounds. In some simulations of this process, you said, the flashes revolve around the black hole, generating a telltale change in their wavelengths before being reflected.
“I love that we can ‘feel’ general relativity in these simulations,” said Dr. Kara said in an email.
Eat your heart, Pink Floyd.