New, "Luminous" Galaxies Are a Wild Bunch

August 10, 2007

Astronomers just got new glasses—and they're helping reveal the universe at its wildest.

A new study has found unusually large, prolific galaxies dating back to just two billion years after the universe formed around 13.7 billion years ago.(Explore a virtual solar system.)

Using new telescope technologies, a global team of 25 researchers are chronicling the galaxies' early lives, when they churned out stars a thousand times faster than the Milky Way, astronomers say.

"It's a real surprise to find galaxies that massive and luminous existing so early in the universe," said astronomer and lead study author Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics.

Astronomers had believed smaller, dimmer galaxies were much more common in the early universe, because it takes time for galaxies to form and grow. (Related: "Eight New Neighboring Galaxies Found, Scientists Announce" [January 10, 2007].)

The findings were published this week in the Astrophysical Journal.

Sharper Focus

Astronomers believe the galaxies are so violent, with new stars constantly colliding and merging, that they also churn out massive amounts of dust. (Related: "Colossal Four-Galaxy Collision Discovered" [August 7, 2007].)

Grant Wilson, an assistant professor of astronomy at the University of Massachusetts and a co-author on the new paper, said astronomers once underestimated the rate of early star formation in bright, active galaxies because their dust hid the starlight.

But because the new galaxies are so massive and hot, their stars heat the surrounding dust to about -387 degrees Fahrenheit (-233 degrees Celsius)—about twice as warm as dust in the Milky Way.

Those are perfect conditions for astronomy's newest tools—telescopes that are built to capture nonvisible light—to detect the galaxies, experts say.

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