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Researchers discuss massive black hole at Tucson conference

By Sarah Spivack
Arizona Daily Wildcat
September 11, 1998
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Arizona Daily Wildcat

Photo Courtesy of UA Physics Department Fulvio Melia, assistant head of physics and professor of astronomy, seen here in this picture from the UA Physics Department Web page, will be participating in the Central Parsecs Galactic Center Workshop this week. The workshop looked at the possible existence of a super-massive black hole.

International astro-nomers and physicists came to Tucson this week to discuss evidence for the existence of a black hole in the center of the galaxy.

UA sci-entists colla-borated with researchers from the Max Plank Institute in Bonn, Ger-any, to organize the Central Parsecs Galac-tic Center Workshop. Participants included Australian and German re-searchers and a Nobel laureate from the Uni-versity of Cali-fornia at Berkeley.

More than a dozen UA researchers and graduate students have examined the nature of an immense volume of dark matter at the galactic center. During the past few years, researchers found evidence that the matter is concentrated into small areas.

Fulvio Melia, conference co-chairman and ass-ociate head of the UA physics de-partment, said that 2.6 million solar masses of matter is packed into a radius of 0.06 light-years. That means there is "either a very exotic structure like nothing we've ever encountered before, or a black hole" Melia said.

UA physics and astronomy department re-searchers made obser-vational and theoretical advances that may enable them to see the event horizon of the black hole in five to 10 years.

An event horizon is "the surface beyond which we can see nothing - including light. Everything is trapped beyond this surface," Melia said. Telescopes that pick up radio waves are located in Tucson and through-out the United States to help researchers study the phenomenon.

"These networks act as one gigantic tele-scope, so we can see fine details at a distance," said Marcia Rieke, a UA astronomer.

Images produced by the radio telescopes have unprecedented resolution, Melia said. They detect details as small as one astronomical unit - 93 million miles - as far away as at the galactic center.

Rieke works with the NICMOS camera on the Hubble space telescope which takes photographs using infrared light and detects images with the resolution of one-thousandth of a light-year.

The images pro-duced by the camera have given scientists indirect information about the galactic black hole.

"We can see the speeds at which stars move near the black hole," Rieke said. Stars are being pushed by the gravitational field of the large mass of dark matter.

Sarah Spivack can be reached via e-mail at Sarah.Spivack@


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