For the first time, astronomers have been able to trace the movement of gas in some of the earliest galaxies we know. They discovered that the gas moves like a whirlpool, similar to in modern galaxies like the Milky Way.
The researchers observed two small newborn galaxies that existed just 800 million years after the Big Bang. Their study, published in Nature, highlights how these young galaxies are already showing a certain degree of order in their movement, something that the team was not expecting to find.
"In the early universe, gravity caused gas to flow rapidly into the galaxies, stirring them up and forming lots of new stars – violent supernova explosions from these stars also made the gas turbulent," lead author Dr Renske Smit, from the University of Cambridge, said in a statement. "We expected that young galaxies would be dynamically 'messy', due to the havoc caused by exploding young stars, but these mini-galaxies show the ability to retain order and appear well regulated. Despite their small size, they are already rapidly growing to become one of the 'adult' galaxies like we live in today."
The observations were only possible thanks to the Atacama Large Millimeter/submillimeter Array (ALMA). The Observatory sees the universe in far-infrared wavelengths and was capable of detecting a special emission from ionized carbon atoms. Without this unique fingerprint, the team wouldn’t have been able to observe the motion of the gas.
"Until ALMA, we've never been able to see the formation of galaxies in such detail, and we've never been able to measure the movement of gas in galaxies so early in the universe's history," added co-author Dr Stefano Carniani, also from Cambridge.
The new study provides several new insights into galaxies in the early universe. These two objects have a mass five times smaller than our own Milky Way, which is common in these primordial galaxies, but they are forming stars at a more efficient rate than other young galaxies from the same epoch.
There is a lot that we still don’t know about the formation and evolution of galaxies, especially in the early universe. New telescopes coming online within the next decades will help us get a clearer idea of what was going on.
This research is being presented at the 231st meeting of the American Astronomical Society.