Features Friday, January 09, 2015 - 05:30
The News Minute | January 6, 2015 | 9:15 am IST Astronomers have observed the largest X-ray flare ever detected from the supermassive black hole at the center of the Milky Way galaxy. This event, detected by NASA’s Chandra X-ray Observatory, raises questions about the behavior of this giant black hole and its surrounding environment. The supermassive black hole at the center of our galaxy, called Sagittarius A*, or Sgr A*, is approximately 4.5 million times the mass of our sun. On Sept. 14, 2013, a team detected an X-ray flare from Sgr A* 400 times brighter than its usual, quiet state. This “megaflare” was nearly three times brighter than the previous brightest X-ray flare from Sgr A* in early 2012. After Sgr A* settled down, Chandra observed another enormous X-ray flare 200 times brighter than usual. The researchers have two main theories about what caused Sgr A* to erupt in this extreme way. The first is that an asteroid came too close to the supermassive black hole and was torn apart by gravity. The debris from such a tidal disruption became very hot and produced X-rays before disappearing forever across the black hole's point of no return, or event horizon. “If an asteroid was torn apart, it would go around the black hole for a couple of hours – like water circling an open drain – before falling in,” said co-author Fred Baganoff of the Massachusetts Institute of Technology in Cambridge, Massachusetts. “That’s just how long we saw the brightest X-ray flare last, so that is an intriguing clue for us to consider.” If this theory holds up, it means astronomers may have found evidence for the largest asteroid to produce an observed X-ray flare after being torn apart by Sgr A*. A second theory is that the magnetic field lines within the gas flowing towards Sgr A* could be tightly packed and become tangled. These field lines may occasionally reconfigure themselves and produce a bright outburst of X-rays. These types of magnetic flares are seen on the sun, and the Sgr A* flares have similar patterns of intensity. Such rare and extreme events give us a unique chance to use a mere trickle of matter to understand the physics of one of the most bizarre objects in our galaxy. Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars.  They can also see various things that the atmosphere blocks out to the naked eye, like the large dust arms of our galaxy. This is what our night sky would look like if there was no atmosphere. (Picture Courtesy - National Geographic) Space agencies are exploring our solar system and beyond to understand the universe and our place in it. The agencies seek to unravel the secrets of our universe, its origins and evolution, and search for life among the stars. Tweet
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