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(Photo: NASA, ESA, R. Ellis (Caltech), and the UDF 2012 Team)

UA Astronomers Glimpse Galaxies Near Cosmic Dawn

The deepest images to date from Hubble yield the first statistically robust sample of galaxies that tells how abundant they were close to the era when galaxies first formed.

“We found the most distant galaxies yet identified and were able to reliably determine their age,” said Brant Robertson, an assistant professor of astronomy at the University of Arizona’s Steward Observatory and one of the main contributors to the research. 

The results show a smooth decline in the number of galaxies with increasing look-back time to about 380 million years after the big bang. The observations support the idea that galaxies assembled continuously over time and also may have provided enough radiation to reheat, or re-ionize, the universe a few hundred million years after the big bang, lending supportive evidence to a critical but still poorly understood milestone in the history of the universe. 

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