Start with a "C" [tone]. Now pitch it down an octave [tone]. Now go one more [tone]. Now go down about 54 octaves more, and you'll have the galaxy-altering peal of a supermassive black hole.
Astronomers have found evidence of this black-hole music in a couple of galaxies. In particular, they've seen big rings and loops of gas surrounding the black holes in the galaxy's cores -- the result of pressure waves from just outside the black holes.
Supermassive black holes inhabit the cores of most or all of the large galaxies. They may surround themselves with disks of superhot gas.
In many cases, the swirling disks produce magnetic fields that shoot out "jets" of particles. As the jets fire through the gas around the black hole, they create pressure waves that push the material outward. Since sound is a pressure wave, the jets are basically creating musical "notes" about 56 to 58 octaves below middle C.
An example is in the galaxy M87. An orbiting X-ray telescope discovered a ring of superhot gas centered on the black hole that's 85,000 light-years across -- a deep musical note resonating across the galaxy.
M87 is in the south at nightfall. It's near the center of a triangle formed by the bright stars Arcturus, which is high overhead; Spica, which is due south; and the pairing of Regulus and the planet Saturn in the southwest. Small telescopes reveal the galaxy as a smudge of light -- a galaxy with a song in its heart.
Script by Damond Benningfield, Copyright 2008
For more skywatching tips, astronomy news, and much more, read StarDate magazine.
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