New findings suggest galaxies formed earlier than previously thought

First panel shows a bright galaxy, indicated by the cross, in an infra-red view. In the second panel, the same region is shown at optical wavelengths. The galaxy has disappeared, indicating it has a redshift between 5-7.

(CNN) -- New evidence that large numbers of galaxies formed earlier than previously though may force researchers to rethink their ideas about how galaxies formed, astronomers said this week.

Numerous bright galaxies are now being detected at very high redshift, indicating they are older and formed even earlier than previously thought.

The term "redshift" describes a shift in spectral light that occurs when the light source is moving rapidly away from an observer. The phenomenon is used by astronomers to calculate the age of stars.

Astronomers at Durham University in the United Kingdom say they have indentified large numbers of galaxies with redshifts between 4 and 6.

That means they were already in existence about 10 billion years ago, when the universe was six times smaller than it is now, the astronomers said in a statement.

Because of the finite speed of light, pictures of very remote galaxies (identifiable because their redshifts have high values) record them as they appeared many billions of years ago, or even in the process of formation, astronomers said.

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Observations of this kind directly test cosmological theories about how and when galaxies formed, the Durham team said.

Popular current cosmological theories predict that few galaxies should be seen with high redshifts.

Now, new red and infra-red pictures have been taken of small areas of the sky already targeted by the deepest ultraviolet and blue surveys. The new images extend the search for galaxies to higher redshifts than ever before.

The work was presented last week during the International Astronomical Union General Assembly in Manchester, England.

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University of Durham
The International Astronomical Union

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