Virtual telescope provides historical view of black hole

Big week for physics: Super-massive black hole imaged days before particle collider test

Using a virtual telescope more than 2,800 miles across, an international team of astronomers got the closest image ever of what they're calling a super-massive black hole in the middle of our galaxy.

It's been a big week in cosmology and physics. On Wednesday, scientists made the first test run of the Large Hadron Collider, sending a single beam traveling at the speed of light around the 17-mile vacuum-sealed tube buried under on the Franco-Swiss border. The test was a forebear to the time when scientists will accelerate two particle beams toward each other at 99.9% of the speed of light. It's all part of a quest to find out how the universe was formed and to better understand dark matter and black holes.

Just days before the particle collider test, the international team of astronomers, led by researchers at the MIT Haystack Observatory, pulled down the best image mankind has ever seen of the black hole, whose mass is believed to be 4 million times that of the sun.

Sheperd Doeleman, a research astronomer at the MIT lab, explained that radio dishes in Hawaii, Arizona and California were linked together to create a virtual telescope capable of seeing details more than 1,000 times finer than the Hubble Space Telescope.

Doeleman said each dish records the radio waves that come from just outside of the black hole on banks of hard disk drives. They then use a super computer to combine the signals from the widely separated radio telescopes. It creates a data set that they use to image the black hole.

The black hole, known as Sagittarius A, was discovered 30 years ago, but astronomers have never been able to get this good a look at it. A black hole is thought to be an object so dense that its massive gravitational pull makes it impossible for anything, even light, to ever escape its draw. Long hypothesized but not yet proven, black holes are studied by the light that is emitted by matter that heats up as it's pulled closer and closer to the anomaly.

Doeleman noted that the black hole seen by the virtual telescope is at the center of the Milky Way. And he added that astronomers now believe that these super-massive black holes can be found at the core of most galaxies.

"I think this is quite important," he said. "The gravity from the black hole is so intense that it bends light just like a lens would. Black holes are these extremes where the laws of physics tend to break down. This is a portal through which matter and radiation disappear and are lost forever. Einstein's theory of general relativity has not been tested in a region of such strong gravitational pull.

"By observing the light just outside the black hole, we can test that theory and make sure the behavior of matter we see is consistent with what [Einstein] predicted. It speaks to the fundamental nature of the universe. Physicists are always asking if the laws of nature apply equally everywhere, or do we live in a special place in the universe? To test that you have to go somewhere else and ask the same questions we do here on Earth."

Doeleman said he thinks the work they're doing will provide a new window into black hole physics.

Copyright © 2008 IDG Communications, Inc.

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