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Astronomers find biggest space blast ever observed

The eruption was seen in a Chandra image of the hot, X-ray emitting gas of a galaxy cluster named MS 0735.6+7421.

This event was caused by gravitational energy release, as enormous amounts of matter fell toward a black hole. Most of the matter was swallowed, but some of it was violently ejected before being captured by the black hole. “I was stunned to find that a mass of about 300 million suns was swallowed,” said Brian McNamara of Ohio University in Athens, Ohio. “This is as large as another super massive black hole.” He is lead author of the study about the discovery, which is in the January 6, 2005, issue of the research journal Nature.

Astronomers are not sure where such large amounts of matter came from. One theory is that gas from the host galaxy quickly cooled and was swallowed by the black hole, which sucks up cool material more easily than hot. The energy released shows the black hole in MS 0735 has grown dramatically during this eruption, the researchers said. Previous studies suggest that other large black holes have grown very little in the recent past, and that only smaller black holes are still growing quickly.

“This new result is as surprising as it is exciting,” said co-author Paul Nulsen of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. “This black hole is feasting, when it should be fasting.”

Two vast cavities extend away from the super massive black hole in the cluster’s central galaxy. Each cavity is about 650,000 light years wide, the researchers said. A light year is the distance light travels in a year.

The eruption, which has lasted for more than 100 million years, has generated energy equivalent to hundreds of millions of gamma-ray bursts, which were previously thought to be the most powerful explosions in the universe. Jets from the black hole evidently erupted to create the cavities, researchers said. Gas is being pushed away from the black hole at supersonic speeds over a distance of about a million light years. The displaced gas contains an amount of material equivalent to the weight of a trillion suns, more than all the stars in the Milky Way, according to the scientists.

NASA’s Chandra X-ray Observatory, a telescope which sees X-rays emitted from extremely energetic objects, detected the explosion. It isn’t visually spectacular but is massive and very powerful, “like a nuclear blast without the light,” McNamara said. While the astronomer previously has spotted and studied these cosmic bubbles of hot gas elsewhere in the universe, “what literally almost knocked me off my chair was the scale, the magnitude of this,” said McNamara, an associate professor of physics and astronomy at Ohio University. Chandra observers have discovered other cavities in galaxy clusters, but this one is easily the largest and the most powerful, the researchers said.

“Until now we had no idea this black hole was gorging itself,” said co-author Michael Wise of the Massachusetts Institute of Technology in Cambridge, Mass. “The discovery of this eruption shows X-ray telescopes are necessary to understand some of the most violent events in the universe.”

The two cavities could explain a longstanding puzzle for astronomers, McNamara said: why some galaxies don’t create new stars as they cool down. Cooling gas in space is believed to create stars because the gas clumps up more easily when it is cold. The clumps of gas eventually become so dense they ignite. McNamara and his colleagues argue that gigantic space bubbles might generate heat that prevents the gas from chilling down and creating stars.

The new study supports recent theories that supermassive black holes have a major impact on the structure of our universe, McNamara said. The volume of space the black hole occupies is about the size of our solar system, he said, but it impacts a volume of space much greater than that – about 600 times the size of the Milky Way galaxy. “From this tiny region of space, the energy is spread out over enormous distances.”

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