Microquasar Discovered -Reveals Clues to Black Holes

Ngc7793 NGC 7793 is one of the brightest galaxies within the Sculptor Group, a group of galaxies in the constellation of the same name. A black hole in outer spiral about the size of our sun in the outer spiral of this galaxy emits spectacular jets.

An international team of astronomers led by Dr. Manfred Pakull at the University of Strasbourg in France has discovered a ‘microquasar’ – a small black hole, Called S26, weighing only as much as a star, that shoots jets of radio-emitting particles into space. The black hole sits inside the galaxy, which is 13M light-years away in constellation Sculptor.


Pakull and colleagues have made new observations with CSIRO’s Compact Array radio telescope near Narrabri, NSW Australia that show that S26 is a near-perfect analogue of much larger ‘radio galaxies’ and ‘radio quasars’ that are almost extinct today, but once dominated the early Universe, billions of years ago and contain gigantic black holes, billions of times more massive than the Sun, and shoot out huge radio jets that can stretch millions of light-years into space.

Astronomers have been working for decades to understand how these black holes form their giant jets, and how much of the black hole’s energy those jets transmit to the gas they travel through. That gas is the raw material for forming stars, and the effects of jets on star-formation have been hotly debated.

"Measuring the power of black hole jets, and therefore their heating effect, is usually very difficult," said co-author Roberto Soria (University College London), who carried out the radio observations.
"With this unusual object, a bonsai radio quasar in our own backyard, we have a unique opportunity to study the energetics of the jets."

Using their combined optical, X-ray and radio data, the scientists were able to determine how much of the jet’s energy went into heating the gas around it, and how much went into making the jet glow at radio wavelengths.

They concluded that only about a thousandth of the energy went into creating the radio glow, which
"suggests that in bigger galaxies too the jets are about a thousand times more powerful than we’d estimate from their radio glow alone," said Dr. Tasso Tzioumis of CSIRO Astronomy and Space Science.

"That means that black hole jets can be both more powerful and more efficient than we thought, and that their heating effect on the galaxies they live in can be stronger."

Casey Kazan via CSIRO

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