Things were different when the Universe was young. In fact, stars used to form much faster 13 billion years ago, according to a study by Pascal Oesch and co-workers. Within a mere 670 million years, EGS-zs8-1 in the constellation Boötes had amassed more than 15% of the total mass of the Milky Way.
The team used a combination of the Keck Observatory on Mauna Kea in Hawaii and the Spitzer and Hubble space telescopes to probe the most distant parts of the Universe. Their spectroscopic measurements of EGS-zs8-1 confirm that it is the brightest and most distant galaxy (apart from a gamma-ray burst 630 Myr after the Big Bang). Crucially, this source dates back to the 'cosmic reionization epoch', when interstellar neutral hydrogen became ionized, and which has been challenging to study. The massive young stars formed rapidly and interacted with the primordial gas.
The James Webb Space Telescope, due to launch in 2018, will help us delve further into our past to clarify the composition and formation of the early Universe.
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Chiao, M. When we were young. Nature Phys 11, 443 (2015). https://doi.org/10.1038/nphys3364
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DOI: https://doi.org/10.1038/nphys3364
