Astronomers in Japan have made an incredible discovery. They have detected oxygen in the distant galaxy SXDF-NB1006-2, which is located 13.1 billion light years away. Using data from the Atacama Large Millimeter/submillimeter Array (ALMA), researchers saw what the primordial galaxy looked like just 700 million years after the Bing Bang. Findings of the study were published Thursday in the journal Science.
Oxygen was a rare element
Heavy elements like oxygen were extremely rare soon after the Big Bang 13.8 billion years ago. Akio Inoue, an astronomer at Osaka Sangyo University and lead author of the study, said in a statement that studying heavy elements would help us understand what caused cosmic reionization and how the galaxies were formed. After the Big Bang, all the atoms in the universe were split into electrons and hydrogen ions due to extremely high temperatures.
These electrically charged ions absorbed most of the universe’s light, preventing it from traveling freely. Then about 380,000 years after the creation of the universe, things cooled down and the ionized particles recombined into atoms. It allowed the first light emitted by the Big Bang to shine. But there were no stars at the time. This period is called the “Dark Ages.” The universe began emerging from the Dark Ages about 150 million years after the Big Bang due to “cosmic reionization.”
The discovery of oxygen in the galaxy SXDF-NB1006-2 could offer clues about the cause of cosmic reionization. Reionization, which lasted more than 500 million years, played a crucial role in the creation of the universe as we know it today. Clumps of cosmic gas and dust clouds began to coalesce to form the first stars and galaxies. Intense UV light from these first objects ionized neutral gasses like hydrogen.
What ionized oxygen tells us about cosmic reionization
Astronomers look at objects as far away as possible to study the ancient cosmic objects because the further away they are, the more time their light took to reach Earth. In the past, some scientists suggested that black holes might have caused reionization, while others claim it was triggered by massive stars. The oxygen detected by Japanese scientists was ionized. They added that oxygen in SXDF-NB1006-2 was 10 times less abundant than in was in the sun.
The presence of ionized oxygen indicates that the galaxy had a large number of young, massive stars. Scientists also found that SXDF-NB1006-2 had far less cosmic dust than there should be. The shortage of dust in that galaxy is believed to have helped cosmic reionization by allowing light from SXDF-NB1006-2 to ionize gas particles outside the galaxy.