June 23, 2024

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The birth of the first galaxies

The birth of the first galaxies

Three galaxies that formed less than 600 million years after the Big Bang tell the story of the universe’s first light

Since its launch two years ago, the James Webb Space Telescope (JWST) has become our best instrument for observing the early universe. Thanks to its ability to see farther away, this instrument has allowed us to discover the oldest galaxies ever known.

His latest discovery has nothing to envy.

Triple birth. A team of astronomers I think you noticed For the first time, three galaxies were born at the dawn of our universe, in the era known as reionization. This observation is made possible thanks to the work of the James Webb Space Telescope (JWST), a telescope designed specifically for these missions.

3% of the way. These galaxies are supposed to have formed more than 13,000 million years ago, that is, between 400 and 600 million years after the Earth appeared. the great explosion. In other words, the universe was only 3% of what it is today.


This isn’t the first time Webb has looked forward to this era of our universe, but it may be the first time we’ve seen a galaxy “awaken” in this early universe. The main event because this is exactly the era in which light appeared in the universe, the era of reionization.

Reionization. We connect the great explosion To a big explosion, and just like that, with a flash of light. The problem is that the universe was too dense for photons to move. When the universe stopped being so dense, the “explosion” was no longer active and the only thing that formed was stable hydrogen.

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“These galaxies are like bright islands in a sea of ​​dark gases.” He explained in a press release Casper Heintz, co-author of the work. Because when this gas began to accumulate and form stars, light appeared in the universe.

This is also not the first time that the James Webb Space Telescope has provided us with important clues about this dawn of the universe.

Time Machine. the job It was based In the data collected by the James Webb Telescope and, more specifically, in its spectrograph specialized in the infrared sector of the electromagnetic spectrum (NIRSpec). The team used what is called a Lyman-alpha (Lyman-α) transition for their analysis. This transformation occurs as light is absorbed by clouds of neutral gas surrounding the emitting source.

It was thus possible to distinguish the background gas of newly formed galaxies. Job details were recently published In an article In the magazine Sciences.

Work ahead. The team is cautious when interpreting the data. Among the points that remain to be clarified for the team are key issues such as the relative position of the gas in relation to these first galaxies, or whether this gas is “pure hydrogen” or if heavier elements were already present in these beginnings.

Therefore, there is a lot of work ahead of us. The team explains that the first step will be to search for more similar observations, thus building a database that allows for statistically confirmed conclusions. In this way it will be possible to verify the validity of this discovery, thus opening a new path to exploring the early history of our universe.

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In Chataka | The James Webb Telescope and Hubble agree that the universe is expanding. Physics cannot explain why.

Image | Illustration of the gas clouds that formed the first galaxies. NASA, ESA, Canadian Space Agency, Joseph Olmstead (STScI)