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Strange red galaxies a 'missing link' in history of the universe?

The discovery of four ruby-red, dim galaxies at the farthest fringes of the universe could help scientists understand how the earliest galaxies evolved to become what we see today.

This artist's conception portrays four extremely red galaxies that lie almost 13 billion light-years from Earth. Discovered using the Spitzer Space Telescope, these galaxies appear to be physically associated and may be interacting. One galaxy shows signs of an active galactic nucleus, shown here as twin jets streaming out from a central black hole.

David A. Aguilar/CfA

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A quartet of rarely observed, ruby-red galaxies from the dawn of the universe could provide a "missing link" in understanding how galaxies formed, according to a new study.

The galaxies, which researchers estimate formed before the 13.7 billion-year-old universe had reached its one billionth birthday, were a puzzle to the team that discovered them. Only one other galaxy like them had been spotted before, and researchers sought to understand why the four galaxies were as red and dim as they appear.

The data could help scientists trying to piece together the story of how the first galaxies formed, as well as how galaxies evolved from humble beginnings to form the variety of sizes, shapes, and star populations seen today in nearby regions of the universe.

These galaxies "might be a missing link in galactic evolution," notes Giovanni Fazio, a researcher at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and a member of the team reporting the results, in a statement.

The galaxies appeared in data gathered by NASA's Spitzer Space Telescope, which observes at longer infrared wavelengths than Hubble. That means Spitzer is in a better position to snag objects – like these galaxies – that shine more brightly in the infrared than in visible wavelengths.

"Hubble has shown us some of the first protogalaxies that formed, but nothing that looks like this," said Dr. Fazio.

Still, the international team reporting the results pushed data-analysis techniques to their limit to tease out the dim galaxies. The team, headed by the Center for Astrophysics' Jiasheng Huang, also had to grapple with why the galaxies were so red and dim. Three options seemed possible:

  • The galaxies could host a large population of older, redder stars and be somewhat closer than the 12.7 billion light-year distance.
  • They could be extremely dusty and even closer.
  • They could be so distant that the universe's expansion has stretched the wavelengths of light they emit deep into the infrared portion of the electromagnetic spectrum.

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