Astronomers detect surprisingly huge galactic birthplace in the first universe



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Back at the dawn of the Universe, astronomers found a stack of cosmic proportions. At least 21 galaxies, forming stars at lightning speed, merge together in the early stages of forming a galaxy cluster. And all of this happens 13 billion light years away – barely 770 million years after the Big Bang itself.

This is the first protocol discovered to date, named LAGER-z7OD1, and today it has probably evolved into a cluster of galaxies 3.7 quadrillion times the mass of the Sun.

Such a grand protocol, so early in the Universe – barely a cosmic nod since the curtain was lifted on life, the Universe, and all – could contain vital clues as to how the primordial smoke s ‘is dispelled and the lights on, sending the light streaming freely. through space.

Our Universe is a massively interconnected place. Galaxies may appear relatively self-contained, but more than half of all galaxies are linked by gravity in clusters or groups, huge structures of hundreds to thousands of galaxies.

The beginnings of such groups are not unknown in the early Universe. Protocols have been found almost as far away as LAGER-z7OD1, some even much larger, suggesting that clusters could start to assemble much faster than previously thought.

But LAGER-z7OD1, according to a team of researchers led by astronomer Weida Hu of the China University of Science and Technology, is special. It can reveal clues to one of the most mysterious stages in the history of the Universe: the era of reionization.

“The total volume of ionized bubbles generated by its member galaxies is comparable to the volume of the Protocluster itself, indicating that we are seeing the individual bubbles merging and the intergalactic medium in the Protocluster is almost fully ionized,” have they wrote in their article.

“LAGER-z7OD1 thus provides a unique natural laboratory to study the process of reionization.”

Space, you see, hasn’t always been the beautiful transparent place it is today. For around 370 million years, it was filled with a hot, cloudy fog of ionized gas. The light was unable to travel freely through this fog; it was scattering free electrons and that was it.

Once the Universe cooled sufficiently, protons and electrons began to recombine into neutral hydrogen atoms. This meant that the light – not that there was still much of it – could finally travel through space.

When the first stars and galaxies began to form, their ultraviolet light reionized neutral hydrogen ubiquitous throughout the Universe: first in bubbles located around ultraviolet sources, then in larger and larger areas when the ionized bubbles connected and overlapped, allowing the entire spectrum of electromagnetic radiation to diffuse freely.

About 1 billion years after the Big Bang, the Universe has been completely reionized. This means that it is more difficult to probe beyond this point (about 12.8 light years away), but it also means that the process of reionization itself is difficult to understand.

Ideally, you need very bright objects whose ionizing radiation could cut neutral hydrogen, and this is what Hu and his team were looking for with the Lyman Alpha Galaxies Investigation during the reionization era. They are small galaxies from the beginning of the Universe forming stars at breakneck speed, which means they can be detected at very great distances, well within the era of reionization. This makes them useful probes of the period.

In their research, the researchers found LAGER-z7OD1, an overloaded region of galaxies in a volume of three-dimensional space measuring 215 million by 98 million over 85 million light-years. This volume contained two separate sub-protocols merging into a larger one, with at least 21 galaxies, of which 16 have been confirmed.

The total volume of ionized space around galaxies was slightly larger than the volume of LAGER-z7OD1.

“This demonstrates substantial overlaps between the individual bubbles, indicating that the individual bubbles are merging into one or two giant bubbles,” the researchers wrote.

So not only does the protocluster represent a prime example of its kind, providing a new data point to study the formation and emergence of these structures, as well as the formation of stars at the start of the Universe, but it provides a window unique on the formation and combination of ionized bubbles in the middle of the reionization epoch.

However, the ideas that will emerge remain to be discovered. As the researchers note, it will be the work of future, more powerful telescopes that can better observe the smallest details of the reionization process.

The team’s research has been published in Nature astronomy.

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