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October 26, 2000 Chandra X-ray sees chaos in universe



by Sylvain Comeau

The universe is a violent place, and we are fortunate to live in one of its best neighbourhoods.

Dr. Eric Feigelson, a Pennsylvania State University professor of astronomy and astrophysics, lectured here last week about the Chandra X-ray Observatory, a NASA project that takes X-ray pictures of the sky. Early results reveal a more chaotic and volatile universe than previously suspected. For example, Chandra is producing pictures of the centre of galaxies, where giant black holes commonly reside.

“The centre of our galaxy is a mess, ladies and gentlemen,” Feigelson said. “It is a violent place, with stars whipping around, colliding with each other, exploding and falling into the black hole. And we don’t fully understand it.”

Feigelson also showed eye-opening slides of Chandra images of the sun, which reveal far more activity than the placid surface we normally see.

“Though it appears peaceful and constant to our unaided eye, to Chandra, the sun exhibits violent magnetic explosions, the equivalent of H-bombs. It looks completely different from our sun, and it looks like that every day.”

In an interview following his lecture, Feigelson explained that Chandra is part of a growing trend in astronomy. “Increasingly, astronomers use non-visible wavelengths of light to study the sky. X-rays see extremely hot things, and it turns out that 10 per cent of all the light and half of all the matter in the universe emit X-rays.”

Astronomers have learned far more about the turmoil and extremes that co-exist with our peaceful solar system. In fact, outer space was thought to be a lot colder than it is.
“Before X-ray telescopes, we never knew that there was anything in the universe that was millions or 100 millions of degrees. We also never knew that half of the atoms in the universe exist at X-ray emitting temperatures, which was never seen with regular telescopes. And we had never even confirmed the existence of black holes.”

Feigelson notes that such observations of a rocking and rolling universe challenge the traditional view of an orderly, peaceful universe. “The visible night sky looks pretty much the same every day. The X-ray sky, in great contrast, reveals things which are pulsing, 100 times a second, things which are flashing, flickering. There are explosions and flares, and a tremendous amount of variability. This does not support the traditional view that stars are eternal and unchanging.”
Feigelson, a member of a research team at Chandra, said in his lecture that no one at the observatory can interpret the data as fast as it comes in. X-ray observation of space has raised many more questions than it has answered, and added fuel to an age-old philosophical and scientific debate.

“The violence we observe once again raises the question of whether the universe is in tune with the emergence of life. Some say that that notion is foolishness, and that we are a random occurrence of atoms and molecules. I’m on the fence on that issue, but I will say that the origin of life is compatible with the physical nature of the universe around us. No magic was involved.

“All the elements of the periodic table come from remnants of supernovas, billions of years ago. They formed, by natural processes, into the atoms and molecules of our world. Now they’re incorporated into a peaceful planet, near a nice, quiet star — a great place for life. So the story of our universe is a richer story than the one we used to tell. It’s a story of both violence and quiescence.”

This lecture was sponsored by the Concordia Science College.