What drives a supermassive black hole?


14/07/2011

The results of the study, during which used data obtained by XMM-Newton X-ray space observatory and the Very Large Telescope, have surprised scientists. Most of the black hole, located in the center of galaxies, in the last 11 billion years intensified the merger of galaxies is not, as previously thought. In the heart of most, if not all, large galaxies, located supermassive black hole whose mass reaches millions, sometimes billions of solar masses. In many galaxies, including our Milky Way, the central black hole is at rest. But in others, especially in the early stages of the universe, the central monster devouring the matter which gives rise to intense radiation as falling into a black hole.

It remains a mystery where does matter, which activates the sleeping black hole and causes severe outbreaks in the center of galaxies, galactic nucleus resulting in an active state. Most astronomers believe that the lion’s share of active cores intensified when two galaxies, or the passage of the two galaxies near each other when under the influence of gravity is shifting matter and becomes fuel for the central black hole. But the new results show that this theory may be wrong for many active galaxies.

Viola Allevato together with an international team of researchers has studied in detail more than 600 active galaxies. As expected, the astronomers found that very bright, active nuclei are rare, and the majority of active nuclei of galaxies over the past 11 billion years were only moderately bright.

But they got a surprise. New data showed that the cause of the majority of active nuclei of these more common, moderately bright galaxies, even in the distant past, it was not a merger of galaxies. The results will be published in The Astrophysical Journal.

"It took more than five years, but we were able to create one of the largest and most complete directory of active galaxies in the X-ray sky," - said Marcella Bruce, one of the study’s authors.

Astronomers can use this new map to find out how active galaxies were distributed in the past and compare the results with theoretical predictions. Also, you can see how this distribution has changed with the development of the universe, from 11 billion years ago, and up until the present day.

Alexis Finogenov who oversaw this work, concluded: "Even in the distant past, up to 11 billion years ago, the merger of galaxies was not the main cause of the moderately bright active galaxies. While galaxies were closer together, and merge occurred more frequently than in later times, so the results are so unexpected. "

Original: Physorg


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