Astronomers used data from NASA’s Chandra X-ray Observatory and the Very Large Array radio telescope to detect a jet from Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way Galaxy.
A jet from the supermassive black hole in the center of Milky Way Galaxy. Image credit: X-ray – NASA / CXC / UCLA / Z. Li et al; radio – NRAO / VLA.
Jets of high-energy particles are found throughout the Universe, on large and small scales. They are produced by young stars and by black holes a thousand times larger than the Milky Way’s black hole.
These jets play important roles in transporting energy away from the central object and, on a galactic scale, in regulating the rate of formation of new stars.
“For decades astronomers have looked for a jet associated with the Milky Way’s black hole,” said Dr Zhiyuan Li from Nanjing University in China, who is the lead author of the paper accepted for publication in the Astrophysical Journal (arXiv.org).
“Our new observations make the strongest case yet for such a jet.”
Sgr A* is about four million times more massive than our Sun and lies about 26,000 light-years from Earth.
Study co-author Dr Mark Morris from the University of California at Los Angeles said: “we were very eager to find a jet from Sgr A* because it tells us the direction of the black hole’s spin axis. This gives us important clues about the growth history of the black hole.”
The study shows the spin axis of Sgr A* is pointing in one direction, parallel to the rotation axis of the Milky Way, which indicates to astronomers that gas and dust have migrated steadily into Sgr A* over the past 10 billion years.
If the Milky Way had collided with large galaxies in the recent past and their central black holes had merged with Sgr A*, the jet could point in any direction.
The region around Sgr A* is faint, which means the black hole has been quiet in the past few hundred years. However, a separate study announced last month shows that it was at least a million times brighter before then.
“We know this giant black hole has been much more active at consuming material in the past. When it stirs again, the jet may brighten dramatically,” said co-author Dr Frederick Baganoff from the Massachusetts Institute of Technology in Cambridge.
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Bibliographic information: Zhiyuan Li et al. 2013. Evidence for A Parsec-scale Jet from The Galactic Center Black Hole: Interaction with Local Gas. ApJ, accepted for publication; arXiv: 1310.0146
