An international team of astronomers has discovered signs of oxygen in a young galaxy called SXDF-NB1006-2, located 13.1 billion light years away. The findings can shed light into how the first stars changed the universe into the universe we know now.
Scientists theorize that the universe was filled with electrically neutral gas before any cosmic object was born. However, a few hundred million years after the Big Bang, the first cosmic objects, including stars, started to produce powerful radiation that ionized this previously neutral gas in a process called cosmic re-ionization.
Still, no one can determine what exactly caused this. to solve this very old mystery, scientists try to seek objects that are far away as possible from us. This is where the most distant galaxy comes in.
The team says that the oxygen they found is ionized. This means that the galaxy contains several stars more massive than the sun. Further investigations on this could reveal how this re-ionization happened, adding more information about the universe.
“Seeking heavy elements in the early Universe is an essential approach to explore the star formation activity in that period,” adds lead author Akio Inoue of Osaka Sangyo University in Japan. “Studying heavy elements also gives us a hint to understanding how the galaxies were formed and what caused the cosmic re-ionization.”
The team employed the Atacama Large Millimeter/Submillimeter Array in Chile. They believed that oxygen in SXDF-NB1006-2 formed 700 million years after the Big Bang.
This very old galaxy contains 10 times less oxygen than our sun. The researchers also found a minute amount of dust composed of heavy metals, which could have allowed the light from cosmic objects to escape and ionize the gas.
They did not find carbon in this distant galaxy, however. Still, the findings are enough to provide a definitive answer to one of the universe’s mysteries. The study will be published in the journal Science this week.
“This is an important step towards understanding what kind of objects caused cosmic reionization,” adds Yoichi Tamura, from the University of Tokyo. “Our next observations with ALMA have already started. Higher resolution observations will allow us to see the distribution and motion of ionised oxygen in the galaxy and provide vital information to help us understand the properties of the galaxy.”