What if the first galaxies had formed earlier than we thought?

The James Webb Telescope has discovered a very old galaxy. This would date from 350 million years after the Big Bang.

And if the first galaxies had formed sooner than we thought ? According to early observations from the James Webb Space Telescope, that might be the case. For the professor of astronomy at UCLA University, Tommaso Treu, “in one way or another, the Universe managed to form galaxies faster and earlier than we thought”.

The James Webb Telescope discovered a very old galaxy

After already five months of observations, James Webb never ceases to amaze us. In particular, he studies the first galaxies formed after the Big Bang, the birth of our Universe, which occurred 13.8 billion years ago. And according to elaborate cosmological models, scientists thought “it would take time” to find them, in the words of astrophysicist Jeyhan Kartaltepe.

But the James Webb is not a telescope like the others. Many very old new galaxies have already been discovered. One of them existed 350 million years after the Big Bang. And these galaxies are extremely luminous: “We immediately draw the conclusion that they are massive, and this raises a real enigma: how could they have formed so many stars in such a short time?”, asks Garth Illingworth , from the University of California at Santa Cruz.

This would date from 350 million years after the Big Bang.

To be so bright today, “these galaxies should have started forming maybe only 100 million years ago. after the big bang. Nobody would have believed that the dark ages would have ended so soon.” It could also be that these galaxies harbor population III stars, very different from those we know. These are extraordinarily bright stars that only exist, to date, in certain theories.

The James Webb telescope has also revealed the appearance of some of these galaxies: “Our team was struck to be able to measure the shape of these first galaxies”, explained Erica Nelson, from the University of Colorado. “Their quiet, orderly disks challenge our understanding of how the first galaxies formed, in a chaotic young Universe.”

These questions are still far from being answered, but one thing is certain, with this new space observatory, “we are really on the right track to realize this dream of understanding the galaxies of the first ages”, enthuses Garth Illingworth.

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