Astronomers a little shaken by the very first image of James Webb

The famous photo shows some of the first galaxies that formed shortly after the Big Bang. And they are very different from expectations…

A few days after the official start of the long-awaited mission of James Webb, the telescope treated us a nice color photo. This deep-field image shows thousands of galaxies, including very young ones that were previously out of sight of all other existing telescopes. Researchers have now taken a closer look at this first photo of James Webb. And that led to the discovery of two unusually and inexplicably bright galaxies in the young universe.

New record
The two particular galaxies are believed to have formed around 350 and 450 million years after the Big Bang. While the exact distance to the galaxies has yet to be confirmed by spectroscopy, it strongly appears that astronomers have broken the record for the most distant galaxies ever found. The previous record holder was the galaxy GN-z11, which formed around 400 million years after the Big Bang. GN-z11 was discovered in 2016 using the Hubble Space Telescope. But it now appears that one of the newly discovered galaxies, GLASS-z12, was born about 350 million years after the Big Bang. This makes this galaxy about 50 million years older than the previous record holder.

Brightness
As mentioned, the extreme brightness of newly discovered galaxies is particularly puzzling. “Luminosity is really a puzzle, challenging our understanding of how galaxies form,” notes study co-author Pascal Oesch. Webb’s observations led astronomers to conclude that a seemingly unusual number of galaxies in the early universe were much brighter than previously thought.

Completely different
Additionally, it appears that the first galaxies formed look remarkably different from the mature ones we see around us today. They appear compressed and spherical or disc-shaped and are also much smaller than our Milky Way galaxy. Additionally, young galaxies are forming new stars at a truly unprecedented rate. Researchers are therefore somewhat troubled by the very first recording of James Webb. “Everything we see is new,” says researcher Tommaso Treu. “Webb shows us that there is a very rich universe that goes beyond what we had imagined. Once again the universe surprised us. These early galaxies are very unusual in many ways.

The two strange newly discovered galaxies. Galaxy number 1 is estimated to have originated 450 million years after the Big Bang and is remarkably elongated. Galaxy number 2 may be even older, forming 350 million years after the Big Bang. The two galaxies are therefore among the oldest and most distant ever discovered. They are also remarkably small compared to the Milky Way. Image: NASA, ESA, CSA, T. Treu (UCLA)

While astronomers have yet to find a conclusive explanation for the mysteries, they offer two possible theories. The first option is that the galaxies are very massive and host low-mass stars, like later galaxies. In contrast, bright galaxies could also harbor population III stars; the very first stars in the universe that have never been observed before.

Population Stars III
Researchers suspect that the very first population of stars formed in the universe were more massive, brighter and hotter than modern stars. They would glow in sweltering temperatures and consist of nothing but primordial hydrogen and helium. And it could also explain the startling properties of the galaxies discovered. “The outermost galaxy is very compact,” said researcher Adriano Fontana. “The colors seem to indicate that the stellar population does not yet contain heavy elements. It could harbor some population III stars. Only further analysis using Webb spectra will reveal this.

Learn more about Population III stars
As mentioned, population III stars are the very first stars to form after the Big Bang. These stars had a very short lifespan – perhaps several hundred thousand years – but they were important for the “evolution” of the universe. These stars rapidly convert light elements into heavier elements, such as oxygen, nitrogen, carbon, and iron. Without these elements we would not be here, because they are very important for the origin of life. These primitive stars have not yet been observed. But the search continues unabated.

Taken as a whole, Webb’s offhand photo completely changes our understanding of how the first galaxies formed in the crowded, chaotic, early Universe. “We were very surprised to find the most distant starlight ever seen, just days after Webb published his first data,” said study co-author Rohan Naidu. Based on all of the predictions, astronomers thought they would have to scour a much larger part of the Universe to find such galaxies. “The observations make your head explode,” adds researcher Paola Santini. “It’s a whole new chapter in astronomy. It’s like an archaeological dig, where a lost city is suddenly found. It’s just breathtaking.