Scientists ID mysterious flash in distant galaxy; observe black hole taking star

Scientists ID mysterious flash in distant galaxy
Thursday, June 16, 2011
BY ALICIA CHANG
ASSOCIATED PRESS

LOS ANGELES — Astronomers think they have solved the mystery of an extraordinary flash spied in a faraway galaxy, saying it came from a massive black hole that devoured a star after it wandered too close.
This artist's image shows a star being distorted by its close passage to a supermassive black hole at the center of a galaxy.
AP
This artist's image shows a star being distorted by its close passage to a supermassive black hole at the center of a galaxy.

The awesome energy released by the feeding frenzy was first detected by NASA's Swift satellite on March 28 and was later confirmed by a fleet of space and ground telescopes.

Some scientists initially thought the bright flash was a gamma-ray burst from a star collapsing, but flaring from such an event typically lasts only a few hours.

Instead of fading, the cosmic outburst continued to burn bright and emit high-energy radiation months later.

Two separate teams pored through data and concluded that an unsuspecting star the size of our sun likely got sucked in by the powerful tug of a giant black hole much like a fly that can't escape a frog resting on a lily pad. The findings were published online Thursday in the journal Science.

As the black hole gobbled up the star, it streamed a beam of energy straight at Earth that was recorded by telescopes. The stellar feast occurred in the heart of a galaxy 3.8 billion light years from Earth. A light year is about 6 trillion miles.

"This was clearly different than anything we've ever seen before," said one of the team leaders, Joshua Bloom, an astronomer at the University of California, Berkeley who classified the event as extremely rare.

Black holes are swirling, super-dense cores of galaxies that vacuum up nearly everything in sight. How they grow so huge remains a mystery. Scientists think the latest observation could help them better understand how galaxies form.

Could what happened in the distant galaxy occur in our Milky Way? In theory yes, say scientists, but the chances are low.

"It's not something worth losing sleep over," said researcher Andrew Levan of University of Warwick in England, who led the other team.

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http://news.sciencemag.org/sciencenow/2011/06/scienceshot-powerful-jet-being.html

On 28 March, NASA’s Swift satellite observed a flash of gamma rays brighter than anything astronomers had seen before. It soon became evident that the event wasn’t a typical gamma ray burst, an emission of high-energy radiation that often accompanies a supernova explosion. The flash didn’t die out but was sustained for weeks, and although it has faded in intensity, it is still going strong 2½ months later. Two papers published online today in Science provide an explanation for this luminous surprise. The flare is in fact a high-energy jet of radiation produced by a star falling into a black hole at the center of a galaxy 4 billion light-years away. The reason the flare is so bright is that the jet is pointed straight in the direction of Earth. And it’s sustained because the black hole is consuming the star gradually. “That’s because as the black hole rips the star apart, the mass swirls around like water going down a drain, and this swirling process releases a lot of energy,” says Joshua Bloom, an astronomer at the University of California, Berkeley, and lead author of one of the two papers. Bloom expects the flare to fade out over the next year.