James Webb telescope discovers old galaxies that shouldn’t even exist

The James Webb Space Telescope has only been fully operational since July last year and has already made several groundbreaking discoveries possible. The latest discovery, which has yet to be confirmed by further measurements, is also a tricky one: it concerns six galaxies from the early days of the universe, which have much more mass than they should have at this early time according to current valid cosmological models. to have. If the facts are confirmed, these common theories should be revised.

According to the current understanding of astronomy, the first stars did not form until about 400 million years after the big bang, which happened about 13.8 billion years ago. Immediately after the big bang, the universe expanded extremely rapidly in a very short time; only after about 300,000 to 400,000 years did the first stable atoms form. During the so-called dark ages before the first stars, the gases in the universe first had to cool enough to form stars and then – about a billion years after the Big Bang – galaxies. According to previous assumptions, the latter formed as small clouds of stars and dust, gradually increasing in size over time.

But what astronomers at Pennsylvania State University and the University of Colorado Boulder found when they viewed the first images from the James Webb telescope last July may contradict this standard model. They saw red dots in the images that were unusually large and bright. Red light is characteristic of very old stars, because as the universe itself expands, the wavelength of light traveling to us from distant galaxies also increases. This shift to the red light spectrum is called redshift. The James Webb telescope, with its infrared instruments, can look back as far as 13.5 billion years – just 300 million years after the Big Bang.

The researchers think the objects are six massive galaxies that formed in the early days of the universe – they had already evolved into galaxies with up to ten billion solar masses about 500 to 700 million years after the Big Bang. One of the galaxies may even have had a stellar mass 100 billion times that of our sun, the astronomers write in the journal Nature. The star clusters contain 100 times more mass than previously believed for this phase of the universe.

The galaxies were already as large as the Milky Way is now, when the Universe was only three percent of its current age – at a time when, according to current theories, there should not have been so much mass to form such large galaxies. “We have never seen galaxies of this colossal size so early after the Big Bang,” said lead researcher Ivo Labbé. And co-author Erica Nelson, assistant professor of astrophysics at the University of Colorado Boulder, explained in a publication on the Eurekalert platform:

According to current knowledge, our own galaxy, the Milky Way, would have formed about 800 million years after the Big Bang, but not in its current size, but only the disk. The surrounding sphere, the galactic halo, would have formed only two billion years later through a merger with a satellite galaxy.

One possible explanation for these strange galaxies would be that the matter density in the young universe could be about two to five times greater than previously believed. However, it is also possible that the galaxies formed in a different, previously unknown way.

Follow-up measurements are currently being made to confirm that the observed points are indeed galaxies and to rule out alternative explanations. While the data suggests they are likely galaxies, other theories are circulating.

Co-author Joel Leja, assistant professor of astronomy and astrophysics at Penn State University, explains: “While the data indicates that these are likely galaxies, I also think it’s possible that some of these objects turned out to be occult supermassive black holes. are from.” Leja therefore believes it is necessary to take a spectral image of the galaxies with the James Webb telescope’s high-resolution near-infrared spectrometer to verify the results.

This could provide astronomers with real-world distance data and information about the gases and other elements that make up galaxies. This information should give a clearer picture of what the galaxies look like and how massive they really are.

Incidentally, this is not the first time that data from the James Webb Space Telescope has been used to discover young galaxies in a phase of the universe in which such star clusters should not have existed. Last year, astronomers discovered four galaxies believed to have formed from gas as early as 350 million years after the Big Bang. However, these objects were downright small, containing only many times the mass of the Sun.

The new discovery shows once again that the investment in the James Webb telescope has paid off. Its high resolution allows it to observe objects that are too old, distant or dim for other telescopes. It can now also turn our cosmological theories and thus our view of the world upside down.