Using the first data set released by NASA’s James Webb Space Telescope, an international team of scientists discovered six massive galaxies in the early universe. These objects are as mature as the Milky Way when the universe was only 3% of its current age, about 500-700 million years after the Big Bang.
The discovery challenges scientists’ understanding of the origin of galaxies in the universe.
Joel Leja, assistant professor of astronomy and astrophysics at Penn State who modeled the light from these galaxies, said: “These objects are much more massive than anyone expected. We expected to find only small, young baby galaxies at this point, but we have discovered galaxies as mature as ours in what was previously seen as the dawn of the universe.”
“This is our first glimpse yet, so it’s important that we keep an open mind about what we see. While the data indicates they are likely galaxies, I think there is a real possibility that some of these objects turn out to be hidden supermassive black holes. Anyway, the amount of mass we’ve discovered means that the known mass in stars in this period of our universe is up to 100 times greater than we previously thought. Even if we cut the sample in half, this is still an amazing change.”
These newly discovered six galaxies are much more massive than anyone expected. They have stellar masses as high as ~1011 solar masses. It was difficult to find massive galaxies even in earlier times, as the Balmer break region, needed for accurate mass estimates, is redshifted to wavelengths beyond 2.5 μm.
leja said, “The revelation that the formation of massive galaxies began extremely early in the history of the universe turns what many of us thought was solid science on its head. We have informally referred to these objects as ‘universe breakers’ – and so far they have lived up to their name.”
It would be necessary to change the cosmological models or to re-evaluate the scientific theory of the formation of galaxies in the early universe, which states that galaxies started as small clouds of stars and dust and grew larger over time in order to to explain a large number of galaxies. mass. Both hypotheses require a major change in how we perceive the origin of the universe.
leja said, “We looked into the very early universe for the first time and had no idea what we would find. It turns out we found something so unexpected that it throws science into trouble. It raises the whole picture of the early formation of galaxies in doubt.”
“Once we got the data, everyone just started diving into it, and these huge things came out quickly,” Leja said. “We started modeling and trying to figure out what they were because they were so big and bright. My first thought was that we’d made a mistake, and we’d just find it and move on with our lives. But we have yet to find that flaw, despite much trying.”
“One way to confirm the team’s findings and allay any remaining concerns is to perform a spectrum image of the massive galaxies. That would provide the team with data on the actual distances as well as the gases and other elements that made up the galaxies. The team could then use the data to paint a clearer picture of what the galaxies looked like and how massive they really were.”
- Ivo Labbe, A population of red candidate massive galaxies ~600 Myr after the Big Bang, Nature (2023). DOI: 10.1038/s41586-023-05786-2