Astronomers from the University of Cambridge have been using ALMA to gain insight into early galaxy formation, taking place 800 million years after the Big Bang.
As our universe was just forming, a few hundred million years after the Big Bang, a dense hydrogen gas fog also filled up the newly formed space. With time, massive black holes began emerging as a result of stars and quasars powering them and cleared away this dense mist.
Until now, astronomers were only capable to view the first early galaxies appearing as faint blobs because of this mist, yet scientists have found a way around this impediment. They used the power of the Atacama Large Milimeter/Submilimeter Array to capture the faint shine of ionized carbon.
In order to do so, scientists led by Roberto Maiolino, trained the ALMA telescope to look past the bright light of mature quasars and bright galaxies and capture the shine of much less evident ones. They aimed ALMA at some of the oldest galaxies discovered.
Surrounding BDF 3299, one of these ancient galaxies, they identified ionized carbon. This recent find allows astronomers to witness how the first galaxies formed so many millions of years ago.
“For the first time we are seeing early galaxies not merely as tiny blobs, but as objects with internal structure,” Andrea Ferrara, study co-author said.
Ionized carbon had an important role in early galaxies’ assembly process, because the dense gas clouds it belonged to served as the building blocks of those galaxies. The period during which the dense clouds surrounding early-forming galaxies began to disappear is called the reionization period.
For decades, scientists have been attempting to understand reionization sources and the ALMA telescope has finally provided data that may help with that endeavor. Researchers will now test predictions and hypotheses regarding star and galaxy formation closely following the Big Bang.
Photo credits: ESO