When the first stars appeared, it was a memorable moment for the Universe, but it is an unknown and obscure idea for researchers. In a new study, however, a team of astronomers has detected some of the most ancient galaxies ever found.
These galaxies were already completely formed when the Universe was 680 million years old, as per the researchers, who also discovered proof that these objects were beaming their surroundings with powerful ultraviolet radiation.
That flood of radiation generated massive bubbles, where the neutral gas became energized and ionized, providing astronomers with the first-ever direct picture of a significant transformational era in our Universe.
Just Before Inception
The Universe was allegedly empty a long time ago, and incredibly neutral. Also, in the first hundred thousand years after the Big Bang, it was so powerfully hot and dense that it was constructed of plasma, and the repeated arm-in-arm pushing had torn up atoms into their element electrons and nuclei.
Apparently, all that mess ended when the Universe got to 380,000 years old. That’s when the electrons were able to merge with their nuclear series due to the low temperature and create the first atoms of hydrogen and helium. When that happened, a violent amount of radiation was generated, that we still know of currently: the cosmic microwave background.
Slowly, over eons, the first stars and galaxies began to form in that dark and neutral space. There is no evidence on how the first stars took shape, but researchers allegedly know when they formed, due to the fact that the Universe is not neutral anymore – it is ionized.
When the Universe was 380,000 years old, it changed from plasma into a neutral gas, but now, about 13 billion years later, almost all of it is plasma again. Whatever triggered this ‘reionization’ must have taken place rather early on.
Researchers believe that the powerful ultraviolet radiation ejected by the first stars and their deaths is the cause behind the Universe becoming plasma again. However, they do know exactly when; even the most advanced telescopes and deepest analyses cannot glance back that far into the Universe.
Back to Plasma
The situation is, however, prone to change. The quest is on for more ancient galaxies, together with analyses of the gas in their vicinity, as researchers try to understand this significant young phase in the development of the Universe. Not long ago, an international team of scientists has discovered three galaxies that are incredibly dim, extremely small, and surprisingly faraway.
These tiny galaxies were already completely formed and functioning when the Universe was just 680 million years old, the researchers claimed. The team has analyzed the radiation emerging from the trio and found out that the galaxies had already started to eject bubbles of ionized plasma into their vicinity. This means that the objects had begun transforming the Universe around them, making it the first definite sign of the event of reionization in progress.
These galaxies are some incredible targets for the forthcoming James Webb Space Telescope, which is specially created to analyze this period in the history of our Universe.
The study has been published in the preprint server arXiv.org on January 7th.