Astronomers believe that the first galaxies formed around giant dark matter halos. However, the newly discovered galaxy, whose history dates back approximately 13 billion years, mysteriously appeared long before this process was expected to occur. The James Webb Space Telescope (JWST) has found a galaxy so large that it should not have existed in the early universe, posing a “significant challenge” to the standard model of cosmology, according to the study’s authors.

The galaxy, called ZF-UDS-7329, contains more stars than the Milky Way, although it formed only 800 million years ago, and the universe has a lifespan of 13.8 billion years. This means that they were somehow born without dark matter to initiate their formation, contrary to what the standard model of galaxy formation suggests.

It’s unclear how this could happen, but like previous JWST discoveries of other inexplicably massive galaxies in the early universe, it threatens to upset our understanding of how the first matter in the universe formed and perhaps even the Standard Model of cosmology. The researchers published their findings Feb. 14 in the journal Nature.

“The existence of these extremely massive galaxies in the universe at such an early stage poses serious challenges to our Standard Model of Cosmology,” said study co-author Claudia Lagos, professor of astronomy at the International Center for Radio Astronomy Research. Lagos added that this is because huge dark matter structures, which are thought to be the necessary components to hold early galaxies together, have not yet formed at such an early stage in the universe.

Light moves at a constant speed through the vacuum of space, so the deeper we look into the universe, the further away the light is captured and the further back in time we go. This is what allowed researchers to use JWST to detect ZF-UDS-7329 about 11.5 billion years ago.

By examining the spectra of light from the stars of this extremely distant galaxy, researchers found that the stars were born 1.5 billion years before this observation, or about 13 billion years ago.

Astronomers aren’t sure when the first balls of stars began clustering in the galaxies we see today, but cosmologists previously estimated that the process began slowly during the first few hundred million years after the Big Bang.

Current theories suggest that halos of dark matter (the mysterious and invisible substance believed to make up 25% of the modern universe) combined with gas to form the first seeds of galaxies. Some 1-2 billion years into the life of the universe, the first protogalaxies reached adolescence and evolved into dwarf galaxies that began to engulf each other to become galaxies like ours.

But a new discovery disproved this view: Not only did the galaxy crystallize without enough dark matter to fuel it, but shortly after the sudden burst of star formation, the galaxy suddenly went quiet, meaning that star formation stopped.

“This pushes the boundaries of our current understanding of how galaxies form and evolve,” study co-author Temiya Nanayakkara, an astronomer at Swinburne University of Technology in Australia, said in a statement. “The question now is how they formed so quickly in the early stages of the Universe, and what mysterious mechanisms caused them to stop forming stars while the rest of the Universe suddenly stopped forming stars.”

The researchers’ next steps will be to search for similar new galaxies. If they found it, they said, it could seriously contradict previous ideas about how galaxies form.