Unraveling the Chaotic Beauty: The Early Galaxies of Our Universe

Recent research reveals that the first galaxies in the universe were quite chaotic. Led by astronomer Lola Dunhaive from Cambridge University, scientists used the James Webb Space Telescope (JWST) to observe 272 small galaxies that formed between 800 million and 1.5 billion years after the Big Bang. At this stage, the universe was still young, and the galaxies looked very different from the neat shapes we observe nearby today.

Dunhaive noted that these early galaxies “were more turbulent, less stable, and grew up through bursts of star formation.” While we see smooth spinning disks in nearby galaxies, these ancient ones had gas flowing in all directions, creating wild turbulence and shock waves.

As the researchers studied these galaxies, they were reminded of the “dawn of disks.” This refers to a time when galaxies were still stabilizing but went through many instabilities before taking on the familiar shapes we see now. The turbulent gas dynamics observed in these galaxies indicate they were ramping up star formation, preparing for an intense burst of activity known as the “Cosmic Noon,” expected to occur just a bit later.

In these early galaxies, star formation wasn’t smooth or orderly. New stars, much like energetic children, created chaos as they blasted out powerful stellar winds and high-energy radiation. This made the surrounding space turbulent and uneven. Interestingly, during this period, gas clouds in the universe were denser—a result of the universe being smaller back then. This density caused more intergalactic gas to flow into these young galaxies, further stirring up turbulence. Additionally, the supermassive black holes at their centers were voraciously feeding on this gas, contributing to the chaos with their jets of radiation.

Many of the galaxies Dunhaive and her team studied were actually quite small, weighing between 100 million and 10 billion times the mass of our sun. In contrast, the Milky Way weighs around 1.5 trillion solar masses. These small galaxies were heavily influenced by their chaotic surroundings, facing disruptive forces from both new star formation and black holes.

Interestingly, while most of the observed galaxies were messy and unstable, some managed to stabilize a bit earlier. These exceptions tended to be larger, which likely helped them withstand cosmic disruption better than their smaller peers. This finding aligns well with current models of galaxy formation, which predict that early galaxies would be clumpy and chaotic.

Dunhaive and her colleagues aim to deepen their understanding by combining observations of ionized hydrogen gas with those of colder gas and dust in these galaxies. This will provide greater insight into how these turbulent systems evolved into the orderly spirals we see today. “With more data, we’ll track how these turbulent systems grew up,” Tacchella added.

The results of their study were published in the Monthly Notices of the Royal Astronomical Society on October 22.

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