Astronomers have discovered the brightest galaxy yet found in the early Universe and found strong evidence that examples of the first generation of stars lurk within it.
The team, led by David Sobral from the Institute of Astrophysics and Space Sciences, the Faculty of Sciences of the University of Lisbon in Portugal, and Leiden Observatory in the Netherlands, peered back into the ancient Universe, to the reionization period approximately 800 million years after the Big Bang.
The newly found galaxy, named CR7, is three times brighter than the brightest distant galaxy known up to now.
Keck Observatory was tremendously important in spectroscopically confirming what are now the most luminous of these distant sources, including the most luminous, the CR7 galaxy (COSMOS Redshift 7), said Sobral, adding that the Keck II telescope fitted with the DEIMOS instrument spectroscopically confirmed CR7 in 15 minutes, even though the galaxy is 13 billion light years away.
By unveiling the nature of CR7 piece by piece, researchers understood that not only had they found by far the most luminous distant galaxy, but also started to realize that it had every single characteristic expected of Population III stars. Those stars were the ones that formed the first heavy atoms that ultimately allowed us to be here.
Within CR7, bluer and somewhat redder clusters of stars were found, indicating that the formation of Population III stars had occurred in waves, as had been predicted.
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What the team directly observed was the last wave of Population III stars, suggesting that such stars should be easier to find than previously thought: they reside amongst regular stars, in brighter galaxies, not just in the earliest, smallest, and dimmest galaxies, which are so faint as to be extremely difficult to study.
The results have been accepted for publication in The Astrophysical Journal.