Astronomers Detected Clear Sign of Oxygen In Galaxy 13.1 Billion Light Years Away from Earth
A team of international researchers have detected gas containing clear signs of oxygen in one of the most distant galaxies 13.1 billion light years away from Earth.
The discovery, published in the journal Science, could help the researchers understand how young stars ionized oxygen and other heavier elements during the cosmic reionisation period 150 million years after the big bang.
"Seeking heavy elements in the early Universe is an essential approach to explore the star formation activity in that period," said lead author Akio Inoue from Osaka Sangyo University in Japan, in a statement. "Studying heavy elements also gives us a hint to understand how the galaxies were formed and what caused the cosmic reionisation,"
For the study, researchers performed computer simulations to predict their chances of detecting ionized oxygen in distant galaxies. They then performed high sensitivity observation using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile.
The researchers then detected light from ionized oxygen in the galaxy SXDF-NB1006-2, which lies at a redshift of 7.2, meaning that we see it only 700 million years after the Big Bang. SXDF-NB1006-2 was discovered in 2012 and has been confirmed by multiple observatories to be the most distant galaxy discovered at the time.
"Our results showed this galaxy contains one tenth of oxygen found in our Sun. But the small abundance is expected because the universe was still young and had a short history of star formation at that time," said Naoki Yoshida, the Project Professor at Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), in a press release.
The presence of the ionized oxygen in the galaxy is a strong indication that any very brilliant stars, several dozen times more massive than the Sun, have formed in the galaxy and are emitting the intense ultraviolet light needed to ionize the oxygen atoms.
However, researchers were not able to detect any emission of carbon in the galaxy, suggesting that the young galaxy contains very little un-ionized hydrogen gas. The researchers also discovered little amount of dust, which is made up of heavy elements, in the galaxy.
The researchers are not set to conduct another observation using higher resolution with ALMA 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.