Black hole emits giant jets

Posted by Staff writer

Please don't snigger, but ESO and NASA astronomers have discovered a black hole blowing out an enormous bubble of hot gas.

The bubble, 1,000 light-years across, is being created by the most powerful pair of jets ever seen from a stellar black hole. The gas-blowing black hole, or microquasar, is located 12 million light-years away, in the outskirts of the spiral galaxy NGC 7793.

"We have been astonished by how much energy is injected into the gas by the black hole," says lead author Manfred Pakull.

"This black hole is just a few solar masses, but is a real miniature version of the most powerful quasars and radio galaxies, which contain black holes with masses of a few million times that of the Sun."

Black holes release huge amounts of energy when they swallow matter, and it had been thought that most of this emerged in the form of radiation. However, the new findings show that some black holes can release at least as much energy, and perhaps much more, in the form of collimated jets of fast moving particles.

The fast jets slam into the surrounding interstellar gas, heating it and triggering an expansion. The inflating bubble contains a mixture of hot gas and ultra-fast particles at different temperatures.

The astronomers discovered that the bubble of hot gas is inflating at a speed of almost one million kilometres per hour. From the size and expansion velocity of the bubble the astronomers have found that the jet activity must have been ongoing for at least 200 000 years.

"The length of the jets in NGC 7793 is amazing, compared to the size of the black hole from which they are launched," says co-author Robert Soria. "If the black hole were shrunk to the size of a soccer ball, each jet would extend from the Earth to beyond the orbit of Pluto."

Very powerful jets have been seen from supermassive black holes, but were thought to be less frequent in the smaller microquasar variety. The new discovery suggests that many may simply have gone unnoticed.

The report appears in Nature.