Astronomers probing how black holes shape galaxies` development
Washington: Astronomers have used a worldwide network of radio telescopes to find evidence that a powerful jet of material that is propelled at almost the speed of light by a galaxy`s central black hole is blowing massive amounts of gas out of the galaxy.
The researchers said that this process is limiting the growth of the black hole and the rate of star formation in the galaxy, and thus is a key to understanding how galaxies develop.
Scientists proposed two major mechanisms that would slow or halt the process of mass growth and star formation-violent stellar winds from bursts of star formation and pushback from the jets powered by the galaxy`s central, supermassive black hole.
The scientists studied a galaxy called 4C12.50, nearly 1.5 billion light-years from Earth.
They chose this galaxy because it is at a stage where the black-hole `engine` that produces the jets is just turning on. As the black hole, a concentration of mass so dense that not even light can escape, pulls material toward it, the material forms a swirling disk surrounding the black hole.
Processes in the disk tap the tremendous gravitational energy of the black hole to propel material outward from the poles of the disk.
At the ends of both jets, the researchers found clumps of hydrogen gas moving outward from the galaxy at 1,000 kilometers per second.
One of the clouds has much as 16,000 times the mass of the Sun, while the other contains 140,000 times the mass of the Sun. The larger cloud, the scientists said, is roughly 160 by 190 light-years in size.
The scientists also said their observations indicate that the jets from the galaxy`s core can stretch and deform clouds of interstellar gas to expand their `pushing` effect beyond the narrow width of the jets themselves. In addition, they reported that, at 4C12.50`s stage of development, the jets may turn on and off and so periodically repeat the process of removing gas from the galaxy.
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