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Monday, January 5, 2004



Far galactic aging
stuns Mauna Kea
researchers

Astronomers see the early universe
mature sooner than expected


HILO >> Astronomers using the Gemini North telescope on Mauna Kea have discovered evidence that the early universe matured much more quickly than previously thought.

In distant areas where they expected to find small, youthful galaxies acting like "firecrackers," they found large, mature galaxies glowing with moderate amounts of light, said Gemini Associate Director Jean-Rene Roy.

Astronomers are not yet sure whether the findings will require a major overhaul of their theories about the early universe.

"It is unclear if we need to tweak the existing models or develop a new one in order to understand this finding," said Patrick McCarthy, of the Carnegie Institution, one of three principal astronomers who worked on the project.

The findings of the team, whose project was called the Gemini Deep Deep Survey, were released today at a meeting of the American Astronomical Society in Atlanta.

The farther away from Earth astronomers look, the older the light of galaxies is, compared with the present, but the younger it is compared with the beginning of the universe in a big bang, thought to have taken place 13.7 billion years ago.

The Gemini Deep Deep Survey looked at four areas of the sky determined to hold galaxies as they looked 3 billion to 6 billion years after the big bang. Because of their movement away from Earth, the light of such galaxies is "shifted" and becomes strongly reddish.

Astronomers call the area the Redshift Desert not because it is empty, but because it is hard to separate the reddish glow of the galaxies from the faint, nighttime glow of Earth's atmosphere.

Other astronomers had gotten around the problem by looking at galaxies that co-principal astronomer Roberto Abraham, of the University of Toronto, called "flashy" because of star formation, the same ones Roy called "firecrackers."

The Gemini team, using a special technique to look into the Redshift Desert, discovered that the majority of galaxies there are not "flashy," but also that they are large, indicating they grew to maturity at an early age.

"These highly developed galaxies, whose star-forming youth is in fact long gone, just shouldn't be there, but are," said Karl Glazebrook, of Johns Hopkins University, the third co-principal astronomer on the team.

Carnegie's McCarthy summed up the meaning of the discovery: "Obviously there are some major aspects about the early lives of galaxies that we just don't understand."

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