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Supermassive black holes


Astronomers have found evidence of a massive cosmic belch expelled by a black hole that gulped the equivalent of 300 million suns.

The twin bubbles billowing from opposite sides of the engorged beast have been spreading outward since the time that dinosaurs roamed the Earth.

Scientists are stunned by the scale of the ongoing eruption coming from the heart of the no-name galaxy cluster MS 0735 in deep space. It is the largest, most energetic outburst ever observed - its plumes stretch more than 6 trillion miles, and are so powerful they have swept a vast swath of interstellar dust and gas from the heavens.

The giant voids left in the eruption's wake are too hot and empty for new stars to form. That may help solve a nagging mystery: why some galaxies don't have as many stars as expected.

"I almost fell out of my chair" upon seeing the first pictures, said Ohio University astrophysicist Brian McNamara, whose team reported its findings today in the journal Nature.

The discovery illuminates black holes' ability to expel matter, not just consume it, in the process transforming almost unimaginably large stretches of the cosmos.

"It shows quite dramatically that black holes can affect space on an enormous scale," McNamara said. "It's clear that supermassive black holes play a fundamental role in shaping the universe."

Team members calculated that the black hole jets gushing from MS 0735 started up 100 million years ago. Over time, they've unleashed the power of nearly a billion exploding stars.

"When you first see them, it takes a while to sink in how big this is," said Paul Nulsen of the Harvard-Smithsonian Center for Astrophysics and a co-author of the Nature paper. "At first you say, 'How interesting.' Then you work out how far away it is and realize . . . it's a remarkable object."

Supermassive black holes are exotic gravitational whirlpools lurking at the center of galaxies or clusters of galaxies. They are the result of the collapse of a large, spent star whose bulk has been squeezed down by the force of gravity into an infinitely small, infinitely dense point in space.

Writers and science fiction filmmakers typically portray black holes as one-way celestial quicksand pits from which nothing - not even light - can escape. But that's only true within a zone of no return near the black hole's maw.

Outside this boundary, atoms of interstellar gas and dust that are being sucked toward the black hole heat up and start shedding their electrons under the tremendous pull.

That lets loose jets of X-rays and electromagnetic waves that shoot from either side of the black hole at nearly the speed of light. Like a tsunami, the erup tions blast away everything in their path, leaving two spreading, super-hot cavities in space.

Astronomers had spotted a few such cavities in nearby galaxies beginning in the early 1990s, McNamara said, but lacked the tools to study them in detail. That changed when space shuttle astronauts released NASA's Chandra X-ray telescope into orbit in July 1999.

The sensitive instrument snares X-rays beaming from high-energy regions of space, like the halos of hot gas and dust that ring galaxy clusters. The halos are stellar incubators. They cradle the raw material for new stars. As the clouds cool and condense, their nuclear fuses should spark, creating a star.

But the sky holds far fewer stars than it should, given the available ingredients in galaxy clusters like MS 0735, the one the team observed. "This puzzle has been around for more than 20 years," Nulsen said. "Why isn't the gas cooling down and forming stars?"

The answer may be that eruptions from big black holes are sterilizing their surroundings - sweeping away some stellar components and heating up what remains so it can't coalesce into stars.

"It's like condensation on a bathroom mirror," McNamara said. "If you want to prevent it, you point the blow dryer at the mirror. As it turns out, these jets are like cosmic blow dryers."

Giant black hole eruptions could be a kind of built-in governor, curbing the amount of star formation in the galaxy clusters they inhabit.

"What this probably explains is why there's a size limit to galaxies," Nulsen said. "It doesn't stop them from getting very big, but it means once you get to a certain size, the process just stops."

Astronomers still don't know the source of all the material the black hole has swallowed over its lifetime, enabling its remarkable growth. It may have dined just on the halo of its own host galaxy cluster, or - less likely - gobbled a passing galaxy and merged with another black hole.

Another unknown: Has the black hole been a constant eater, or has it binged on everything in sight and then gone dormant until enough material collected to re-stoke its metabolism? "We don't know if matter fell in at a constant rate," McNamara said. "You could shovel it in all at once, or shovel slowly."

Those are welcome challenges for future research

"It's interesting to be reminded that we're a long way from understanding things," Nulsen said.

Sir stephen hawkins has a theory that through black holes when can reach an early time or time travel but the only thing holding back the research is the black hole part of the eqaution.


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