Astronomers have detected a clear signal from oxygen in a galaxy located 13.1 billion light years from Earth, making it the most distant oxygen ever discovered.
The amount of oxygen in SXDF-NB1006-2, a galaxy discovered in 2012 and confirmed as being the most distant galaxy discovered at the time, is ten times smaller than that observed in the Sun, they reported Thursday in the U.S. journal Science.
"The small abundance is expected because the Universe was still young and had a short history of star formation at that time," study author Naoki Yoshida of the University of Tokyo said in a statement.
Using data from the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile, a team of researchers from Japan, the U.S. and Europe made the discovery that could help understand the enigmatic "cosmic reionization" in the early history of the universe.
Various elements are found around us in the present Universe, but just after the Big Bang 13.8 billion years ago only the lightest elements, hydrogen, helium, and lithium, existed.
Then, several hundreds of millions of years after the Big Bang, the first stars began to develop, emitting strong radiation that ionized the neutral gas and synthesized heavier elements such as carbon and oxygen.
This is a period known as "cosmic reionization" that eventually created the universe we are familiar with today.
The new observations showed only a very small amount of dust, which is made from heavy elements, exists in SXDF-NB1006-2, which could be an indication that almost all the gas in the galaxy, including oxygen, is highly ionized, the researchers said.
"This is the first step to understanding what kind of objects caused cosmic reionization," said Yoichi Tamura of the University of Tokyo, who is co-author of the study.
"Our next observations with ALMA have already started. Higher resolution observations will allow us to see the distribution and motion of ionized oxygen in the galaxy and provide precious information to understand the properties of the galaxy."
