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Subaru telescope discovers a rosetta stone cluster of galaxies

Astronomers using the Subaru Telescope have discovered an aggregate of galaxies undergoing a burst of star formation that may hold the key to understanding how galaxies formed in the early universe. The aggregate is located toward the Constellation Vulpecula and is 11 billion light years away (redshift z = 2.5), 2.7 billion years after the birth of the universe.

These baby-booming galaxies may be a proto-cluster, an ancestor of present-day clusters of galaxies; they still seem to be growing into full-size galaxies. By analyzing near-infrared emission data from the Subaru Telescope with mid-infrared emission data from the Spitzer Telescope, the astronomers were able to identify the bright objects in the infrared as members of a primordial cluster.

These primordial galaxies show a very high star formation rate of several hundreds of Suns per year. Such high star formation rates do not occur in any nearby galaxies. In addition, the number of mid-infrared sources apparently exceeds the amount that can be attributed to the objects visible in H-alpha emission. This indicates that there could be more dust-enshrouded galaxies with active star formation.

Image: The 4C 23.56 protocluster area. The red squares show objects (color-coded in green) that emit H-alpha emission lines. The field of view is 3.0 arcminutes by 3.7 arcminutes.

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