The first images captured by the James Webb Telescope have revealed six massive galaxies that formed very soon after the Big Bang. However, the mass of these galaxies is much greater than what astronomers expected to find at this time in the history of the Universe. This discovery is so startling that it could challenge current models of cosmology, or even our understanding of how galaxies formed in the early Universe.
One of the characteristics of the James Webb Telescope (TJW) is that it can see celestial bodies that are much more distant, older and of lower luminosity than the Hubble Space Telescope. It thus makes it possible to observe the genesis of the Universe.
It was by analyzing the first color images captured by the TJW that a team of researchers from Australian, American, Danish and Spanish universities was able to track down six particularly massive galaxies that formed around 600 million years after the Big Bang, and which are described in an article published in the journal Nature.
In December 2022, it was announced that even older galaxies, dating from 350 to 400 million years after the Big Bang had been unearthed thanks to the James Webb telescope, notes Nathalie Nguyen-Quoc Ouellette, deputy director of the Trottier Institute for Research on Exoplanets (iREx) and the Mont-Mégantic Observatory (OMM). “But what’s remarkable about this new discovery is the size, maturity and mass of the galaxies. These are highly developed galaxies, almost as massive as our galaxy, the Milky Way,” she points out.
These galaxies would have masses 100 times larger than astronomers thought they should have so early in the history of the Universe. This discovery upsets their conception of the formation of galaxies in the primordial Universe. “According to what these researchers describe, these galaxies grew faster than previously thought. It’s surprising that the galaxies studied in the article were able to mature so quickly, in just a few hundred million years, to resemble our Milky Way so early in the history of the Universe. These observations go against current cosmological models and the laws of physics that were believed to exist at the beginning of the Universe,” explains Ms. Nguyen-Quoc Ouellette.
The researchers who made this discovery are now working to confirm the age, distance, nature and real mass of these galaxies by further analyzing the spectrum emitted by these galaxies.