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  • Publicado : 21 de marzo de 2011
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Supermassive black hole is thrown out of galaxy
Marianne Heida of the University of Utrecht in the Netherlands, as part of an international team of astronomers, has found what appears to be a supermassive black hole leaving its home galaxy at high speed.

Heida worked at the SRON Netherlands Institute for Space Research, using the Chandra Source Catalog (made using the orbiting Chandra X-rayObservatory) to compare hundreds of thousands of sources of X-rays with the positions of millions of galaxies. Normally each galaxy contains a supermassive black hole at its center. The material that falls into a black hole heats up dramatically on its final journey, and it often means that black holes are strong X-ray sources.

X-rays are also able to penetrate the dust and gas that obscures thecenter of a galaxy, giving astronomers a clear view of the region around the black hole, with the bright source appearing as a starlike point. Looking at one galaxy in the catalog, Heida noticed that the point of light was offset from the center and yet was so bright that it could well be associated with a supermassive black hole.

The black hole appears to be in the process of being expelledfrom its galaxy at high speed. Given that these objects can have masses equivalent to 1 billion suns, it takes a special set of conditions to cause this to happen.

Heida's newly discovered object is probably the result of the merger of two smaller black holes. Supercomputer models suggest that the larger black hole that results is shot away at high speed, depending on the direction and speed inwhich the two black holes rotate before their collision. In any case, it provides a fascinating insight into the way in which supermassive black holes develop in the center of galaxies.

Heida's research suggests this discovery may be only the tip of the iceberg, with others subject to future confirmation using the Chandra Observatory. "We have found many more objects in this strange class ofX-ray sources," said Heida. "With Chandra, we should be able to make the accurate measurements we need to pinpoint them more precisely and identify their nature."

Finding more recoiling black holes will provide a better understanding of the characteristics of black holes before they merge. In the future, it might even be possible to observe this process with the planned LISA satellite, aninstrument capable of measuring the gravity waves that the two merging black holes emit. Ultimately, this information will let scientists know if supermassive black holes in the cores of galaxies really are the result of many lighter black holes merging together.
New Way To Weigh Giant Black Holes
ScienceDaily (July 17, 2008) — How do you weigh the biggest black holes in the universe? One answer nowcomes from a completely new and independent technique that astronomers have developed using data from NASA's Chandra X-ray Observatory.

By measuring a peak in the temperature of hot gas in the center of the giant elliptical galaxy NGC 4649, scientists have determined the mass of the galaxy's supermassive black hole. The method, applied for the first time, gives results that are consistent with atraditional technique.
Astronomers have been seeking out different, independent ways of precisely weighing the largest supermassive black holes, that is, those that are billions of times more massive than the Sun. Until now, methods based on observations of the motions of stars or of gas in a disk near such large black holes had been used.
"This is tremendously important work since black holescan be elusive, and there are only a couple of ways to weigh them accurately," said Philip Humphrey of the University of California at Irvine, who led the study. "It's reassuring that two very different ways to measure the mass of a big black hole give such similar answers."
NGC 4649 is now one of only a handful of galaxies for which the mass of a supermassive black hole has been measured with...
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