|Artist’s impression of the distant galaxy SXDF-NB1006-2. Many young bright stars are located in the galaxy and ionise the gas inside and around the galaxy. Green color indicates the ionised oxygen detected by ALMA, whereas purple shows the distribution of ionised hydrogen detected by the Subaru Telescope. Credit: NAOJ |
The most distant oxygen ever found in the universe was recently detected by scientists using Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile.
The cosmic oxygen was discovered in one of the most distant galaxies known, SXDF-NB1006-2, which lies at a redshift of 7.2, meaning that we see it on Earth only 700 million years after the Big Bang.
In the time before objects formed in the Universe, it was filled with electrically neutral gas. But when the first objects began to shine, a few hundred million years after the Big Bang, they emitted powerful radiation that started to break up those neutral atoms — to ionise the gas. During this phase — known as cosmic reionisation — the whole Universe changed dramatically. But there is much debate about exactly what kind of objects caused the reionisation. Studying the conditions in very distant galaxies can help to answer this question.