The National Aeronautics and Space Administration said the Chandra X-ray Observatory had monitored for 53 hours noise coming from the central region of the Perseus galaxy cluster.

The pitch of the sound waves, equivalent to a B-flat -- 57 octaves lower than a middle-C and at a frequency far deeper than the limits of human hearing -- is the deepest note ever detected from an object in the universe, researchers said.

Bruce Margon, associate director at the Space Telescope Science Institute in Baltimore, Maryland described the sound at a press conference here as being "a million, billion times deeper than the limits of human hearing."

Scientists believe the sound waves are produced by explosions occurring around a supermassive black hole in Perseus A, the huge galaxy at the center of the cluster.

"These sound waves may be the key in figuring out how galaxy clusters, the largest structures in the universe, grow," said researcher Steve Allen of the Institute of Astronomy in Cambridge, England.

A long standing mystery has been why hot gas in the central regions of the Perseus cluster has not cooled off over the past 10 billion years to bring a drop in pressure that would draw gas in towards the galaxy to form trillions of stars.

The researchers suggest that as the sound waves move through gas, they are eventually absorbed and their energy converted to heat. This means that sound waves from the black hole in Perseus A may keep the cluster gas hot.

SPACE.WIRE