Dynamic Tension

EGS-zs8-1

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• published: 12 May 2015
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An international team of astronomers, led by Yale University and University of California scientists, has pushed back the cosmic frontier of galaxy exploration to a time when the universe was only 5 percent of its present age of 13.8 billion years. The team discovered an exceptionally luminous galaxy more than 13 billion years in the past and determined its exact distance from Earth using the combined data from NASA's Hubble and Spitzer space telescopes, and the Keck I 10-meter telescope at the W. M. Keck Observatory in Hawaii. These observations confirmed it to be the most distant galaxy currently measured, setting a new record. The galaxy existed so long ago, it appears to be only 100 million years old. The galaxy, EGS-zs8-1, was originally identified based on its particular colors in images from Hubble and Spitzer and is one of the brightest and most massive objects in the early universe. The new distance measurement also enabled the astronomers to determine that EGS-zs8-1 was still forming stars very rapidly, about 80 times faster than our Milky Way galaxy today (which has a star-formation rate of one star per year.) Only a handful of galaxies currently have accurate distances measured in this very early universe. The discovery was only possible thanks to the relatively new Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) instrument on the Keck I telescope, which allows astronomers to efficiently study several galaxies at the same time. Measuring galaxies at these extreme distances and characterizing their properties is a main goal of astronomers over the next decade. The observations see EGS-zs8-1 at a time when the universe was undergoing very important changes: the hydrogen between galaxies was transitioning from an opaque to a transparent state. These new Hubble, Spitzer, and Keck observations together give a new glimpse into the nature of the infant universe. They confirm that massive galaxies already existed early in the history of the universe, but that their physical properties were very different from galaxies seen around us today. Astronomers now have very strong evidence that the peculiar colors of early galaxies seen in the Spitzer images originate from a very rapid formation of massive, young stars, which interacted with the primordial gas in these galaxies.