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Black holes blow stronger winds than previously thought: study

English.news.cn   2014-02-28 06:37:31

WASHINGTON, Feb. 27 (Xinhua) -- Black holes can release more energy into the galaxies they live in than previously thought, a new study said Thursday.

The discovery, published in the U.S. journal Science, will help astronomers better model the evolution of black holes over time, and it will also help them better understand how these mysterious regions affect their host galaxies.

Black holes are places in space where gravity pulls so much that even light cannot get out.

Black holes grow when gas in space flows or accretes onto them. The gas inside gets so hot it emits radiation.

According to a theory of physics called the Eddington limit, the amount of radiation flowing outward from a black hole cannot exceed a certain limit or it will blow the inflowing gas away. The limit is based on the black hole's mass.

However, whether a black hole's kinetic energy, in the form of jets and winds, is controlled by the same limit has been unclear.

To shed some light on the matter, scientists led by Roberto Soria of Australia's Curtin University used telescopes to study the outflow of a black hole in galaxy M83 for more than a year.

By analyzing the gas flowing into the black hole, they figured out the black hole's weight as less than 100 times that of the Sun.

The researchers compared the mass of the black hole with its outgoing kinetic power, which they were able to infer in part by looking at the light around it.

The kinetic power flowing out of the black hole was higher than the Eddington limit for a black hole of this mass, the researchers found.

These results demonstrate that black holes can "inject more energy into the surrounding medium than would be inferred based on their Eddington limits," the researchers wrote in their paper.

"The existence of super-Eddington mechanical power is important for the modeling of jet production mechanisms, as well as the evolution of fast-growing supermassive BHs (black holes) in the early universe, and their effect on their host galaxies," they added.

Editor: Mu Xuequan
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