NASA tweeted an enigmatic, ghostly melody: a bellow coming from the black hole at the center of the Perseus galaxy cluster. This is sonification, or astronomical data translated into sound waves.
Bewitching, frightening, mysterious: this sound that comes from the black hole located in the galactic cluster of Perseus, about 250 million light years from us, does not leave you indifferent.
NASA has unveiled what scientists call a sonificationor the translation into an audible file of astronomical data.
The Perseus Cluster is one of the most massive objects in the Universe: it contains thousands of galaxies immersed in a huge cloud of superheated gas. In the X-ray image taken by the space telescope Chandra (see top of article), huge light loops, ripples and jet-like streaks can be seen throughout the cluster.
Ripples in Gas
Since 2003, the black hole at the center of the Perseus galaxy cluster is associated with sound. Indeed, astronomers found that pressure waves emitted by the black hole caused ripples in the cluster’s hot gas that could be translated into a note – a note humans cannot hear, fifty-seven octaves below middle C.
The sound waves do not in fact propagate in the interstellar vacuum, but thanks to the mass of gas – a support for the propagation of this chant – the sound becomes concrete. By amplifying it and mixing it with other data, it gives this amazing cry from the depths of space.
This sonification is unlike any other performed before (see for example these pages: 1, 2, 3, 4), as it replicates the actual sound waves discovered in the data from theChandra X-ray Observatory from NASA.
A readjusted frequency
The sound waves were extracted in radial directions, i.e. from the center outwards. These signals were then resynthesized into the range of human hearing by scaling them 57 and 58 octaves above their actual pitch.
They can also be said to be heard 144 quadrillion and 288 quadrillion times higher than their original frequency [ndlr. un quadrillion est égal à 1’000’000’000’000’000]. Radar-like scanning around the image makes it possible to hear the waves emitted in different directions. In the visual image of this data, on the video, the blue and purple both show x-ray data captured by Chandra.
>> A NASA page with the sonification of various cosmic objects: A Universe of Sound
Stephanie Jaquet