Galaxy SXDF-NB1006-2, a distant 13.1 billion light-years from earth, is home to the oldest known oxygen that scientists have ever been able to detect. Glowing in the radiation of young stars, the discovery points the way to a better understanding of the Big Bang and early stages of our universe.
The discovery comes from research into the distant galaxy that was just published Thursday in the journal Science. The paper is authored by a number of different researchers and scientists from Japan, the UK, Sweden, and the European Southern Observatory (ESO), using data from the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile.
What the international team observed was the glow of ionized oxygen in the galaxy. The strong ultraviolet light of many stars, each of them many times larger than our sun, would be required to ionize oxygen to the level that was observed. Study author Akio Inoue of Osaka Sangyo University commented on the importance of the discovery in an interview with Gizmodo.
“These oxygen atoms we found are a kind of the first oxygen ever produced in the Universe, because oxygen did not exist at the Big Bang. In fact, all elements heavier than lithium are produced inside stars and are spread out the Universe when they die.”
Galaxy SXDF-NB1006-2, Oxygen, And The Big Bang
Because of the fact that light takes time to travel over vast distances, we are observing the galaxy SXDF-NB1006-2 as it was about 700 million years after the Big Bang. The Big Bang actually occurred nearly 14 billion years ago, meaning our view of galaxy SXDF-NB1006-2 is the equivalent of looking back in time about 13 billion years to a very new galaxy.
Finding evidence that confirms the presence of oxygen in such a young galaxy is a big development for astronomers. Immediately after the Big Bang, it would have been impossible for life to form. Only light elements such as helium and hydrogen could exist during the initial period that lasted a few hundred thousand years when temperatures were extremely hot. The formation of life requires elements such as carbon and oxygen which are heavier. As the universe cooled, there followed a period called the dark ages. The universe was de-ionized; filled with gas that was electrically neutral.
Today, the universe is an ionized “star factory” according to the Washington Post. During that period between the dark ages and our era, there was a long, slow process of star and eventually galaxy formation. Gradually neutral hydrogen gas began to clump into stars in an evolution that took hundreds of millions of years. However, once it reached a critical mass, the process essentially snowballed. The powerful radiation emitted by young stars began to light up the universe, breaking up neutral atoms and ionizing the gases of the universe during a period known as cosmic reionization.
As reported in Gizmodo, as gases reionized, researchers theorized that it would produce a massive flare of light. That’s the glow they were looking for – and what they found at galaxy SXDF-NB1006-2.
Because of its age, galaxy SXDF-NB1006-2 is believed to be one of the key players in that process. Akio Inoue of Osaka Sangyo University commented in a statement quoted by University of Cambridge News.
“SXDF-NB1006-2 would be a prototype of the light sources responsible for the cosmic re-ionization.”
A Distant Galaxy
Galaxy SXDF-NB1006-2 was discovered in 2012 and at that time it was the oldest and farthest galaxy that humans had ever seen. Initial observation of the galaxy revealed the glow of ionized hydrogen and prompted researchers to continue searching with the Atacama Large Millimeter Array Telescope.
The amount of oxygen discovered in the distant galaxy is small — about one-tenth that of our Sun — but extremely important. Stars begin to produce heavier elements like oxygen and carbon as they age. Finding oxygen in galaxy SXDF-NB1006-2 puts scientists a step closer to being able to determine at what point in the evolution of the universe the very first carbon and oxygen molecules began to form.
There is still a lot of mystery about the cosmic re-ionization period and the study of galaxy SXDF-NB1006-2 brings scientists that much closer to answers. Yoichi Tamura of the University of Tokyo talks about the next step in a media release.
“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 vital information to help us understand the properties of the galaxy.”
[Image via National Astronomical Observatory of Japan/NAOJ]