Black hole eats star, spews light beam

U. WARWICK (UK) — A big, bright bang recorded by astronomers came from a distant black hole that ripped apart a star and blasted an energy beam to Earth.

Details of the observation by astronomers are reported this week in the journal Science.

The high energy X-rays and gamma-rays persisted at an extremely bright level for weeks after the event, with bright flares arising when further chunks of the star apparently fell into the black hole. While at optical and infrared wavelengths, it is as bright as a hundred billion suns.

Artist’s impression of formation of two jets of energy at the black hole Swift 1644+57, which is 3.8 billion light years away from Earth. (Credit: Mark Garlick, University of Warwick)

The extreme brightness of this event comes from the fact that it created a powerful beam of energy pointing a jet of light towards the Milky Way and thus concentrated into only a small fraction of the sky and which was detected at Earth 3.8 billion years after the star was ripped apart.

“Despite the power of this the cataclysmic event we still only happen to see this event because our solar system happened to be looking right down the barrel of this jet of energy,” says lead researcher Andrew Levan of the University of Warwick.

Researchers say the source of this event—known now as Swift 1644+57—is at the heart of far away galaxy, 3.8 billion light years away, at a spot that would be in the constellation Draco. This conclusion comes from a combination of the most powerful telescopes on the ground, and in space, working in tandem to pinpoint this unique and unprecedented event. These include the Hubble Space Telescope, Chandra X-ray Observatory, Swift satellite, and the Gemini and Keck Telescopes in Hawaii.

“The best explanation that so far fits the size, intensity, time scale, and level of fluctuation of the observed event, is that a massive black at the very center of that galaxy has pulled in a star and ripped it apart by tidal disruption. The spinning black hole then created the two jets one of which pointed straight to earth,” says Warwick researcher Andrew Levan.

Nial Tanvir, second author of the paper, based at the University of Leicester, adds: “It is rare for stars to get very close to the black holes in the center of galaxies, but when they do, they will always come off second best.”

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