Black Hole Sound Video Download
Melony Holden
In this new sonification of Perseus, the sound waves astronomers previously identified were extracted and made audible for the first time. The sound waves were extracted in radial directions, that is, outwards from the center. The signals were then resynthesized into the range of human hearing by scaling them upward by 57 and 58 octaves above their true pitch. Another way to put this is that they are being heard 144 quadrillion and 288 quadrillion times higher than their original frequency. (A quadrillion is 1,000,000,000,000,000.) The radar-like scan around the image allows you to hear waves emitted in different directions. In the visual image of these data, blue and purple both show X-ray data captured by Chandra.
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.
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 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.
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 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.
In perfect isolation, it would be impossible to hear a black hole. Hearing requires the presence of sound waves, and the presence of sound waves requires a substance to travel through. This also means that, again in perfect isolation, the process of two black holes merging releases no light and no sound.
But fortunately for us, black holes do not live in isolation. They are constantly surrounded by streams of matter (and usually that matter is on its way to being swallowed by the black hole). And that matter, as thin as it might be, can absolutely support sound waves.
A sonic black hole, sometimes called a dumb hole or acoustic black hole, is a phenomenon in which phonons (sound perturbations) are unable to escape from a region of a fluid that is flowing more quickly than the local speed of sound. They are called sonic, or acoustic, black holes because these trapped phonons are analogous to light in astrophysical (gravitational) black holes. Physicists are interested in them because they have many properties similar to astrophysical black holes and, in particular, emit a phononic version of Hawking radiation.[1][2] This Hawking radiation can be spontaneously created by quantum vacuum fluctuations, in close analogy with Hawking radiation from a real black hole. On the other hand, the Hawking radiation can be stimulated in a classical process. The boundary of a sonic black hole, at which the flow speed changes from being greater than the speed of sound to less than the speed of sound, is called the event horizon.
By accelerating atoms across the dark gap at the centre of this image, researchers think they might be able to create an acoustic black hole capable of producing the first detectable Hawking radiation
An artificial black hole that traps sound instead of light has been created in an attempt to detect theoretical Hawking radiation. The radiation, proposed by physicist Stephen Hawking more than 30 years ago, causes black holes to evaporate over time.
Condensates have been made that move supersonically before, so physicists have likely created acoustic black holes in the process of working with BECs, says Eric Cornell of the University of Colorado at Boulder, who shared a 2001 Nobel Prize for the development of Bose-Einstein condensates.
The team cooled 100,000 or so charged rubidium atoms to a few billionths of a degree above absolute zero and trapped them with a magnetic field. Using a laser, the researchers then created a well of electric potential that attracted the atoms and caused them to zip across the well faster than the speed of sound in the material.
But in the 1970s, Hawking proposed that if the pair was created near the edge of a black hole, one particle might fall in before it is destroyed, leaving its partner stranded outside the event horizon. To observers, this particle would appear as radiation. In acoustic black holes, Hawking radiation would take the form of particle-like packets of vibrational energy called phonons.
Detecting Hawking radiation through astronomical observations, however, is difficult, because the evaporation of typical black holes is obscured by higher-energy sources of radiation, including the cosmic microwave background, the afterglow of the big bang.
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NASA Exoplanets, a team at the agency focused on planets and other information outside of our solar system, tweeted the 34-second clip on Sunday and said there's a "misconception" that there is no sound in space.
NASA's Chandra X-ray Observatory detected sound waves, for the first time, from a super-massive black hole. The "note" is the deepest ever detected from an object in the universe. The tremendous amounts of energy carried by these sound waves may solve a longstanding problem in astrophysics.
The black hole resides in the Perseus cluster, located 250 million light years from Earth. In 2002, astronomers obtained a deep Chandra observation that shows ripples in the gas filling the cluster. These ripples are evidence for sound waves that have traveled hundreds of thousands of light years away from the cluster's central black hole.
"We have observed the prodigious amounts of light and heat created by black holes, now we have detected the sound," said Andrew Fabian of the Institute of Astronomy (IoA) in Cambridge, England, and leader of the study.
In musical terms, the pitch of the sound generated by the black hole translates into the note of B flat. But, a human would have no chance of hearing this cosmic performance, because the note is 57 octaves lower than middle-C (by comparison a typical piano contains only about seven octaves). At a frequency over a million, billion times deeper than the limits of human hearing, this is the deepest note ever detected from an object in the universe.
"The Perseus sound waves are much more than just an interesting form of black hole acoustics," said Steve Allen, also of the IoA and a co-investigator in the research. "These sound waves may be the key in figuring out how galaxy clusters, the largest structures in the universe, grow," Allen said.
Heating caused by a central black hole has long been considered a good way to prevent cluster gas from cooling. Although jets have been observed at radio wavelengths, their effect on cluster gas was unclear since this gas is only detectable in X-rays, and early X-ray observations did not have Chandra's ability to find detailed structure.
Previous Chandra observations of the Perseus cluster showed two vast, bubble-shaped cavities in the cluster gas extending away from the central black hole. Jets of material pushing back the cluster gas have formed these X-ray cavities, which are bright sources of radio waves. They have long been suspected of heating the surrounding gas, but the mechanism was unknown. The sound waves, seen spreading out from the cavities in the recent Chandra observation, could provide this heating mechanism.
A tremendous amount of energy is needed to generate the cavities, as much as the combined energy from 100 million supernovae. Much of this energy is carried by the sound waves and should dissipate in the cluster gas, keeping the gas warm and possibly preventing a cooling flow. If so, the B-flat pitch of the sound wave, 57 octaves below middle-C, would have remained roughly constant for about 2.5 billion years.
Perseus is the brightest cluster of galaxies in X-rays, and therefore was a perfect Chandra target for finding sound waves rippling through the hot cluster gas. Other clusters show X-ray cavities, and future Chandra observations may yet detect sound waves in these objects.
We have created an analog of a black hole in a Bose-Einstein condensate. In this sonic black hole, sound waves, rather than light waves, cannot escape the event horizon. A steplike potential accelerates the flow of the condensate to velocities which cross and exceed the speed of sound by an order of magnitude. The Landau critical velocity is therefore surpassed. The point where the flow velocity equals the speed of sound is the sonic event horizon. The effective gravity is determined from the profiles of the velocity and speed of sound. A simulation finds negative energy excitations, by means of Bragg spectroscopy.
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