The first galaxies may have formed earlier than predicted

published on Thursday, November 17, 2022 at 22:40

The very first galaxies may have formed earlier than astronomers previously thought, according to early observations from the new James Webb Space Telescope, which in just a few months has already shattered scientific understanding of the cosmos.

“One way or another, the universe managed to form galaxies faster and sooner than we thought,” said Tommaso Treu, professor of astronomy at UCLA University.

One of the main tasks of the James Webb Telescope, which is in its fifth month of observations, is to study the first galaxies that formed after the Big Bang 13.8 billion years ago.

Based on sophisticated cosmological models, scientists thought “it would take time” to find them, said astrophysicist Jeyhan Kartaltepe.

In just a few months, however, James Webb has already identified many new young galaxies, including one that existed just 350 million years after the Big Bang – 50 million years short of the previously observed record.

“It’s a surprise that so many formed so early,” commented Jeyhan Kartaltepe.

In addition to their number, one thing amazed the scientists: their high luminosity.

“We immediately conclude that they are massive, and that raises a real puzzle: How could they form so many stars in such a short time?” summarized Garth Illingworth of the University of California, Santa Cruz.

To do that, “these galaxies must have started forming maybe 100 million years after the Big Bang,” he explained. “No one would have believed that the Dark Ages would end so soon”.

An alternative hypothesis would be that these galaxies are indeed host to so-called Population III stars, which are very different from those we know. These very first stars, extraordinarily bright, have only been theorized, not observed.

The incredible capabilities of the James Webb Telescope have also revealed the appearance of some of these galaxies.

“Our team was impressed to be able to measure the shape of these early galaxies,” said Erica Nelson of the University of Colorado, quoted in a NASA statement. “Their quiet, orderly disks challenge our understanding of how the first galaxies formed in a chaotic young Universe.”

The exact distances of these young galaxies – including the one that broke the record – will have to be confirmed in the future thanks to spectroscopic analyzes also carried out with James Webb.

Anyhow, thanks to this new observatory, “we are really on track to realize this dream of understanding the galaxies of the first ages,” marveled Garth Illingworth.

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