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| Chandra image of the Perseus cluster.(NASA/CXC/SAO/E.Bulbul, et al.) |
NASA has released a haunting audio clip of sound waves rippling out of a
supermassive black hole, located 250 million light-years away.
The black hole is at the center of the Perseus cluster of galaxies, and the
acoustic waves coming from it have been transposed up 57 and 58 octaves so
they're audible to human hearing.
The result (below), released by NASA in May, is a sort of unearthly
(obviously) howling that, if we're honest, sounds not only spooky, but a
little bit angry.
It's the first time these sound waves have been extracted and made audible.
So what's going on in this recording? We might not be able to hear sound in
space, but that doesn't mean there isn't any.
In 2003, astronomers detected something truly astonishing: acoustic waves
propagating through the copious amounts of gas surrounding the supermassive
black hole at the centre of the Perseus galaxy cluster, which is now
renowned for its eerie wails.
We wouldn't be able to hear them at their current pitch. The waves include
the lowest note in the Universe ever detected by humans – well below the
limits of human hearing.
But this recent sonification has not only brought the recording up a whole
lot of octaves, they've also added to the notes detected from the black
hole, so we can get a sense of what they would sound like, ringing through
intergalactic space.
The lowest note, the one identified back in 2003, is a B-flat, just over 57
octaves below middle C; at that pitch, its frequency is 10 million years.
The lowest note detectable by humans has a frequency of one-twentieth of a
second.
The sound waves were extracted radially, or outwards from the supermassive
black hole at the center of the Perseus cluster, and played in an
anti-clockwise direction from the center, so that we can hear the sounds in
all directions from the supermassive black hole at pitches 144 quadrillion
and 288 quadrillion times higher than their original frequency.
The result is an eerie one, like many of the waves recorded from space and
transposed into audio frequencies.
The sounds aren't just a scientific curiosity, though. The tenuous gas and
plasma that drifts between the galaxies in galaxy clusters – known as the
intracluster medium – is denser and much, much hotter than the intergalactic
medium outside galaxy clusters.
Sound waves propagating through the intracluster medium is one mechanism
whereby the intracluster medium can be heated, as they transport energy
through the plasma.
Because temperatures help regulate star formation, sound waves might
therefore play a vital role in the evolution of galaxy clusters over long
periods of time.
That heat is what allows us to detect the sound waves, too. Because the
intracluster medium is so hot, it glows brightly in X-rays. The Chandra
X-ray Observatory allowed not only for the detection of the sound waves
initially, but for the sonification project.
Another famous supermassive black hole also got the sonification treatment.
M87*, the first black hole ever to be directly imaged in a colossal effort
by the Event Horizon Telescope collaboration, was also imaged by other
instruments at the same time.
Those include Chandra for X-rays, Hubble for visible light, and the Atacama
Large Millimeter/submillimeter Array for radio wavelengths.
Those images showed a colossal jet of material being launched from the space
immediately outside the supermassive black hole, at speeds that appear
faster than that of light in a vacuum (it's an illusion, but a cool one).
And now, they too have been sonified.
To be clear, these data were not sound waves to start with, like the Perseus
audio, but light in different frequencies. The radio data, at the lowest
frequencies, have the lowest pitch in the sonification. Optical data hold
the middle range, and X-rays are at the top.
Turning visual data like these into sound can be a cool new way to
experience cosmic phenomena, and the method has scientific value, too.
Sometimes, transforming a dataset can reveal hidden details, allowing for
more detailed discoveries about the mysterious and vast Universe around us.
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Tags:
Space & Astrophysics