Detecting Cluster of Young Galaxies in Distant Universe

An international team of astronomers using the millimeter wave camera AzTEC identified a massive galaxy (AzTEC-3) surrounded by cluster of galaxies in development when the universe was only 1 billion years old.

Our current understanding of galaxy formation in the early universe is based on the flow of cold, dark matter regulated by gravity and a negative pressure force known as dark energy. Current theories suggest that galaxy clusters would be rare in such an early epoch of the universe. The detection of this cluster may require modifications to current descriptions of structure and galaxy formation in the universe.

The youngest galaxies contain enormous reservoirs of gas needed to fuel star formation. This gas coexists with dust grains that obscure the optical and ultraviolet light emitted by stars, making these galaxies faint or even invisible to telescopes that operate between the ultraviolet and mid-infrared range of the electromagnetic spectrum. This same dust--warmed by the ultraviolet light of newborn stars--emits radiation at far infrared wavelengths. However, because distant galaxies appear to be receding due to the expansion of the universe, the dust radiation is observed at longer millimeter wavelengths. It is these stretched wavelength signals that AzTEC detected from the proto-cluster in the early universe.

The AzTEC camera was developed at the University of Massachusetts and is deployed on the James Clerk Maxwell Telescope in Hawaii. The effort was led by Professor Grant Wilson of the University of Massachusetts. Follow-up observations that confirmed the presence of a cluster of galaxies surrounding AzTEC-3 at an age of 1 billion years were carried out at the Smithsonian Submillimeter Array and the Keck 10-meter telescope, led by Peter Capak of Caltech with Wilson and Min Yun as collaborators.