QUASAR'S INTENSE GAMMA RAYS SEEN.

Byline: Jane E. Allen Associated Press

Scientists have discovered a spectacular flare from a quasar 10 billion light years away that produced 100 billion times more gamma ray energy than is found in our galaxy.

Scientists using the National Aeronautics and Space Administration's orbiting Compton Gamma Ray Observatory said the 150-minute flare turned the quasar known as PKS 1622-297 into the brightest gamma-ray source in the sky for several days last summer.

``We don't know exactly what it is, that's why it's interesting,'' said John Mattox, a visiting scientist at the University of Maryland astronomy department. ``We're exploring matter under very exotic and extreme conditions.''

Gamma rays are extremely high-frequency radiation at wavelengths shorter than X-rays. Quasars are bright emitters of light and radio waves.

The discovery was reported May 1 at a meeting of the High Energy Astrophysics Division of the American Astronomical Society in San Diego, where scientists announced several new gamma ray findings. It has been submitted for publication in the Astrophysical Journal.

PKS 1622-297 is a type of quasar called a blazar. It's a supermassive black hole at the core of a distant galaxy that captures gas and material from nearby stars, heats it and releases X-rays, gamma rays and jets of material toward Earth at nearly the speed of light.

Since its 1991 launch aboard a shuttle, the Compton Observatory has detected 50 blazars.

At the same meeting, scientists from the Smithsonian Institution's ground-based Whipple Observatory in southern Arizona announced they had detected three examples of a new, highly energetic class of blazar.

The Smithsonian team said such blazars emit gamma rays 1,000 times more energetic than those detected by orbiting spacecraft like Compton.

On Earth, the only way to see such high-energy gamma rays is by creating them with the most powerful particle accelerators. The jets of the newly detected blazars act like cosmic accelerators.

``Given these are 400 million light years away, it's a clue to some very exotic process that's taking place,'' said Trevor Weekes, a Smithsonian astrophysicist. ``It takes all man's ingenuity to build a particle accelerator at Fermilab or Stanford, but it's quite commonplace in nature to produce these jets.''

Scientists characterized the new class of blazar after seeing three examples with a technique that combines arrays of mirrors and light detectors.

In a third announcement, U.S. and British scientists said gamma ray observations found that a seemingly unremarkable galaxy was an energy powerhouse.

A 1994 observation using the Compton Observatory revealed a Seyfert galaxy, known as NGC 4945, to be one of the brightest sources of energetic gamma ray radiation outside our galaxy.

Greg Madejski, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md., said that NGC 4945, located in the constellation Centaurus, appeared like a run-of-the mill galaxy in the visible and X-ray bands of light. That's because such light was mostly absorbed by a thick shroud of matter.

But gamma ray observations let scientists see past the shroud to an object 100,000 times more luminous than the Crab Nebula, left behind in our galaxy by a star explosion 1,000 years ago.

Madejski said the discovery could help scientists distinguish individual sources of background X-ray radiation in the universe.

``This experiment tells us objects just like that might be very important contributors,'' he said.