Thu, Nov 20, 2008

Tucson Region

UA scope sheds new light on black hole

By Aaron Mackey
Arizona DAily STar
Tucson, Arizona | Published: 09.04.2008
A UA radio telescope has helped astronomers capture an unprecedented close-up view of the center of the Milky Way galaxy.
The virtual image, created by combining measurements from radio telescopes at three locations, shows what scientists believe is a supermassive black hole at the center of our galaxy.
It's thought that black holes — superdense objects that suck matter, light and energy into themselves — lie at the center of most galaxies, though the theory hasn't been proved.
The detailed images obtained through the University of Arizona's Submillimeter Telescope on Mount Graham, along with telescopes in Hawaii and California, for the first time put a limit on the size of the object at the center of the galaxy, said Lucy Ziurys, director of the Arizona Radio Observatory and a co-author of a study set to be released today.
"It basically establishes the fact that there really is a black hole in our galactic center," Ziurys said.
Scientists have had difficulty measuring the center of the Milky Way because it is so far away — light emitted from it takes 25,000 years to reach Earth — and galactic materials such as dust and stars obscure optical views, Ziurys said.
Unlike traditional optical telescopes, which measure visible light, radio telescopes use radio frequencies throughout the electromagnetic spectrum to measure distant objects.
Using very short radio wavelengths, the telescopes were able to pierce dust and other objects surrounding the center of the galaxy, linking together to create an image roughly 1,000 times finer than those seen by the Hubble Space Telescope, according to a UA news release.
The result is the most detailed look at the center of the Milky Way yet, Sheperd Doeleman, an astronomer with the Massachusetts Institute of Technology and lead author of the study, said in the press release.
"This technique gives us an unmatched view of the region near the Milky Way's central black hole," Doeleman said in the release. "The new observations have a resolution equivalent to being able to see, from Earth, a baseball on the surface of the moon."
The scientific findings, which will be detailed in an article in the journal Nature, are important to helping astronomers understand the composition of our galaxy, Ziurys said.
Establishing the methods to look into the galaxy while coordinating the telescopes took more than six years, and astronomers already are trying to develop ways to get an even closer look, Ziurys said.
"If you went to even shorter wavelengths, you could get even more detail of the object," she said.
● Contact reporter Aaron Mackey at 807-8012 or at amackey@azstarnet.com. Get all the latest UA news by visiting go.azstarnet.com/ campuscorrespondent.