Earlier in 2014, the team had run large-scale numerical simulations of galaxy formation to conclude that the ALMA telescope would be capable of detecting light from ionized oxygen in SXDF-NB1006-2. This galaxy was discovered in 2012 by the Subaru Telescope operated by National Astronomical Observatory of Japan (NAOJ) and the following observations with Keck Observatory showed that it was the most distant galaxy known at that time (note 1).
Previous research suggested that, after the universe was born in the Big Bang about 13.8 billion years ago, the universe was so hot that all of the atoms that existed were split into positively charged nuclei and negatively charged electrons. We can't actually see the birth of these first stars, because all that hydrogen was pretty opaque, so scientists are always trying to push further and further back in time.
After the Dark Ages, clumps of gas began to break down and form the universe's first galaxies and stars in an era called the reionization. However, 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 ionize the gas. This is known as "cosmic reionization". After this happened, the team say, the whole universe "changed dramatically". Nevertheless, the process is deeply shrouded in darkness, but there is much debate about exactly what kind of objects caused the reionisation.
The lack of dust in the galaxy allows the intense ultraviolet light to escape and ionize vast amounts of gas outside the galaxy.
The research team conducted simulations and found that the old galaxy has two to three times less dust than was predicted, which may have helped in reionization. Especially lights and radiation that remained bouncing in outer space.
About the discovery, Naoki Yoshida, a researcher from the University of Tokyo and co-author of the study, said, "The small abundance is expected because the universe was still young and had a short history of star formation at that time".
One possible explanation for the smaller amount of dust is that shock waves from supernova explosions may have destroyed it, the researchers said.
"Something unusual may be happening in this galaxy". Such highly ionized gases may have played a key role in cosmic reionization.
The detection of oxygen in the galaxy suggests that several stars, many times as larger than the sun, are bathing the galaxy in ultraviolet light, ionizing the gas.
"SXDF-NB1006-2 would be a prototype of the light sources responsible for the cosmic reionisation", said Inoue.
Work is already underway for another observation using the ALMA telescope. "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". The distance stated in that press release is 12.91 billion light-years, but new calculations using the latest cosmological parameters measured with Planck (H0= H0=67.3km/s/Mpc, Omega;_m=0.315, Lambda;=0.685: Planck 2013 Results) yield a distance of 13.08 billion light-years. "In fact, all elements heavier than lithium are produced inside stars and are spread out the Universe when they die".
The researchers intend to keep ALMA focused on SXDF-NB1006-2 to see what else we can find out about stellar processes occurring within it.