04-09-2005 - Space

sagar: Author=’Jorge Salazar’ program=’4479′ video=”Dusty grains – including tiny specks of the minerals found in the gemstones peridot, sapphires and rubies – can be seen blowing in the winds of a quasar in this artist’s concept (NASA)Today, the black holes in the centers of galaxies are relatively quiescent. But billions of years ago, they must have been devouring nearby gas, dust and stars voraciously, causing a huge outpouring of light.

Light travels at a finite speed. That’s why, the farther away we look in space, the deeper we are looking back into the past.

And it takes a very bright light to travel across space for billions of light-years – and still be visible. Quasars are that bright light. A single quasar outshines trillions of suns.

From Earth, quasars look like stars. But they’re not stars. Modern astronomers believe that quasars are associated with galaxies, and with black holes at the centers of galaxies. A quasar might be a black hole in the center of a young galaxy that actively devours the material around it.

Patrick Osmer: What you’ve gotten on to is another one of the great problems of modern astrophysics and cosmology, is how did these galaxies and quasars and black holes form?

That’s Patrick Osmer, a professor and chair of the astronomy department at Ohio State University. He told us that quasars might signal the birth of a galaxy.

Patrick Osmer: What’s exciting is that we now have the power, with telescopes like Hubble and the large ground-based telescopes, to see objects so far away that we’re seeing back to very close to the era when they were first forming. And so, that’s what we’re about here, that quasars, and in fact galaxies, can be observed at those same distances.

Osmer said astronomers now consider quasars to be associated with supermassive black holes that live in the center of galaxies. As materials fall on the black hole – pulled in by the very strong pull of the black hole’s gravity – the material gets very hot. It glows and shines so much that it can outshine the entire galaxy surrounding it. Hence a quasar.

Patrick Osmer: Quasars seem to represent a phase when galaxies, at least massive ones, were really coming together. The materials were falling together to the center. It’s still a mystery of how the central black hole formed, but it’s clearly some process resulting from the collapse of material towards the center of what became a massive galaxy and formed a central black hole. And then as more material fell into it, of course it got greatly heated by the gravitational energy released by falling near the black hole, and thus we could see it, and that’s what made quasars shine so brightly.

Thanks today to Research Corporation, a foundation for the advancement of science.

Our thanks to:
Patrick S. Osmer
The Ohio State University

Written by Jorge Salazar