WASHINGTON, July 16 (Xinhua) -- U.S. scientists have developed a completely new and independent technique to weigh the biggest black holes in the universe using data from NASA's Chandra X-ray Observatory, the Chandra X-ray Center reported on Wednesday.
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 a traditional 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 holes can 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 two different methods. In addition, this new X-ray technique confirms that the supermassive black hole in NGC 4649 is one of the largest in the local universe with a mass about 3.4 billion times that of the Sun, about a thousand times bigger than the black hole at the center of our galaxy.
These results will appear in an upcoming issue of The Astrophysical Journal.
