Amira Shehata wrote Sunday, March 3, 2024 11:00 PM Cannes Universe A very dark place at its beginning, after the glow of the explosive birth of the universe cooled. Space was filled with dense gas, mostly hydrogen, with no sources of light. Slowly, over hundreds of millions of years, the gas was pulled into clumps by gravity. Eventually, the clumps became Large enough to ignite, these were the first stars.
According to the Phys website, at first the light did not travel far, as much of it was absorbed by a fog of hydrogen gas.
However, as more stars formed, they produced enough light to overwhelm the haze by “reionizing” the gas, creating the transparent universe filled with the brilliant points of light we see today.
But what stars produced the light that ended the Dark Ages and launched the so-called “era of reionization?” In research published in the journal Nature, scientists used a huge collection of galaxies as a magnifying glass to look at the faint relics of that time, and they discovered that the stars in the galaxies Small and faint ones were most likely responsible for this transformation on a cosmic level.
What ended the Dark Ages?
Most astronomers already agreed that galaxies were the main force in reionizing the universe, but it was not clear how they did it, and there are two camps among galaxy theory followers.
The first believed that massive galaxies produced ionizing photons. There weren’t many such galaxies in the early universe, but each one produced a lot of light. So, if a certain fraction of that light managed to escape, it might be enough to re-ionize the universe.
The second camp believes that it is better to ignore giant galaxies and focus on the vast number of much smaller galaxies in the early universe.
Each of these elements would have produced much less ionizing light, but given their sheer numbers, they could have ushered in the era of reionization.
Trying to look at anything in the early universe is very difficult. Massive galaxies are rare and therefore difficult to find, but smaller galaxies are more common, but they are very faint, which makes obtaining high-quality data difficult.
Scientists used a massive group of galaxies called the Pandora Cluster as a magnifying glass on what happened. As part of the UNCOVER programme, scientists used the James Webb Space Telescope to look at magnified infrared images of faint galaxies behind the Pandora Cluster.
Observations confirmed that these small galaxies were already present at the beginning of the universe. Furthermore, scientists confirmed that they produced about four times more ionizing light. This is higher than expected based on the understanding of how early stars formed, and given that these galaxies produced a lot of ionizing light. Only a small portion of it would need to escape to reionize the universe.
