If the extreme bass sound known as infrasound produces anxiety, extreme sorrow and chills in people, what would this note do, make an entire nebula soil itself?

Astronomers say they have heard the sound of a black hole singing. And what it is singing, and perhaps has been singing for more than two billion years, they say, is B flat - a B flat 57 octaves lower than middle C.

The "notes" appear as pressure waves roiling and spreading as a result of outbursts from a supermassive black hole through a hot thin gas that fills the Perseus cluster of galaxies, 250 million light-years distant. They are 30,000 light-years across and have a period of oscillation of 10 million years. By comparison, the deepest, lowest notes that humans can hear have a period of about one-twentieth of a second.

The black hole is playing "the lowest note in the universe," said Dr. Andrew Fabian, an X-ray astronomer at the Institute for Astronomy at Cambridge University in England.

....Last year, however, Dr. Fabian and his colleagues obtained a new long-exposure Chandra image of the Perseus cluster, which showed waves moving outward like ripples on a pond from the central bubbles.

The waves, they realized, might be the ideal missing link between the jets and the surrounding gas. Dr. Fabian compared the process to a child's blowing bubbles in a glass of water through a straw. In this case, the jets are the straw. The bubbles pushing against the enormous pressure of the gas surrounding them create sound waves moving out through the cluster's gas, pumping energy into it and heating it.

....The energies are as prodigious as the symphony is boring. It takes the energy of 100 million supernova explosions to blow a central bubble in the cluster. If the black hole blows such bubbles continuously and it is this energy that has been keeping Perseus hot, then the black hole in Perseus must have been playing a steady B flat for a long time, said Dr. Fabian. "It's the longest-lasting symphony we know of," said Dr. Bruce Margon, an astronomer at the Space Telescope Science Institute. [NY Times]