Thursday, September 11, 2003
A B-flat from a galaxy far, far away
After the Hubble space telescope, it is now the turn of the Chandra X-ray observatory to make the most amazing discoveries. Nature reports that Chandra has detected the lowest B-flat ever heard, from a black hole sitting at the heart of the NGC 1275, a galaxy in the Perseus galaxy cluster.
These ripples of high- and low-density gas are like sound waves in air. But their frequency is far lower than the deepest sound audible to the human ear. A piano capable of producing the note would have 57 octaves below middle C and would be more than 15 metres long. The sound waves carry immense amounts of energy away from the black hole, heating up the surrounding gas. Researchers suspected that the gas in clusters such as Perseus must be kept warm, but they did not know how.
These ripples of high- and low-density gas are like sound waves in air. But their frequency is far lower than the deepest sound audible to the human ear. A piano capable of producing the note would have 57 octaves below middle C and would be more than 15 metres long. The sound waves carry immense amounts of energy away from the black hole, heating up the surrounding gas. Researchers suspected that the gas in clusters such as Perseus must be kept warm, but they did not know how.
