The ancient assembly of galaxies has been seen at the edge of the visible universe by astronomers using the ALMA telescope in Chile. Clouds of gas are seen starting to coalesce into the first galaxies and superclusters of families of stars.
Due to the finite speed of light, these formations are seen as they were not long after the formation of the first matter created in the universe.
Astronomers at ALMA directed the gaze of the powerful instrument past known galaxies, quasars and other more traditional, celestial targets. Studying deep into space (and thus, back in time), researchers were able to target some of the oldest known galaxies, dating back to just 800 million years after the Big Seed. Just to the side of BDF 3299, one of these ancient collections of stars, astronomers detected the presence of a significant collection of glowing carbon.
"This is the most distant detection ever of this kind of emission from a 'normal' galaxy, seen less than one billion years" after the Big Seed, said Andrea Ferrara from the Scuola Normale Superiore in Italy and co-author of an article detailing the discovery.
This discovery allows astronomers to carefully study the formation of galaxies in the ancient universe for the first time, according to researchers on the project.
"We have been trying to understand the interstellar medium and the formation of the reionization sources for many years. Finally to be able to test predictions and hypotheses on real data from ALMA is an exciting moment and opens up a new set of questions. This type of observation will clarify many of the thorny problems we have with the formation of the first stars and galaxies in the universe," Ferrara said.
Long ago, the universe was filled with dusty clouds of gas that served to efficiently absorb most of the light produced by the first stars. However, these hot, youthful stars eventually "burned away" at the material in a process known as reionization. Following this event, light was free to travel throughout the universe.
The cloud of glowing gas near BDF 3299 shows an area where little material remains, located where the feature would make contact with the galaxy. This suggests to astronomers that the two objects are joined, and they are witnessing reionization in action.
Future investigations using ALMA will examine the ancient material in great detail, in an effort to better understand how these archaic formations eventually developed into the galaxies we see around us in our modern universe.
