TEHRAN (Press Shia Agency) – Arizona State University astronomers, working with international teams in Chile and China, discovered 23 young galaxies, seen as they were 800 million years after the Big Bang.

Long ago, about 300,000 years after the beginning of the universe (the Big Bang), the universe was dark. There were no stars or galaxies, and the universe was filled with neutral hydrogen gas. In the next half billion years or so the first galaxies and stars appeared. Their energetic radiation ionized their surroundings, illuminating and transforming the universe.

This dramatic transformation, known as re-ionization, occurred sometime in the interval between 300 million years and one billion years after the Big Bang. Astronomers are trying to pinpoint this milestone more precisely and the galaxies found in this study help in this determination.

"Before re-ionization, these galaxies were very hard to see, because their light is scattered by gas between galaxies, like a car's headlights in fog," Arizona State University astronomers Sangeeta Malhotra said.

"As enough galaxies turn on and 'burn off the fog' they become easier to see. By doing so, they help provide a diagnostic to see how much of the 'fog' remains at any time in the early universe," she added.

Junxian Wang, a co-author on this study and the lead of the Chinese LAGER team, added, "Our findings in this survey imply that a large fraction of the first galaxies that ionized and illuminated the universe formed early, less than 800 million years after the Big Bang."

The next steps for the team will be to build on these results. They plan to continue to search for distant star forming galaxies over a larger volume of the universe and to further investigate the nature of some of the first galaxies in the universe.

The results from this study have been published in the Astrophysical Journal.