The James Webb Space Telescope has already spotted some amazing things in its first year of science operations, but if a new study holds water it might be one of the most important finds of all time. A team of astrophysicists proposes that three bright objects detected by Webb in the distant universe could be the first candidate “dark stars,” hypothetical celestial objects powered by the annihilation of dark matter.
Webb’s unprecedented power allows astronomers to look farther away in space and back in time than any other telescope before, but in doing so it keeps discovering things that mess with our understanding of the cosmos. For instance, it keeps spotting galaxies that appear to be too advanced for their age, growing too big in too short a time since the Big Bang. Whether galaxies grow faster than we thought, or the universe is much older than we give it credit for, it seems that something in our models needs tweaking.
In a new study, astrophysicists propose an alternative – perhaps, some of the objects we’re seeing in the early universe aren’t galaxies at all, but “dark stars.” More than just an oxymoron or a cult 70s sci-fi movie, a dark star is a hypothetical object that doesn’t shine from nuclear fusion like normal stars, but instead generates heat from dark matter particles annihilating with each other in the core.
If they exist, dark stars would be much larger than regular stars, containing the mass of 10 million Suns and emitting the brightness of 10 billion – although not in visible light but infrared. They’d also be 10,000 times wider, meaning that if the Sun was a dark star it would fill the entire solar system, with its outer surface located somewhere near the orbit of Pluto.
Models suggest that dark stars should be possible in the early universe, and could actually help explain the mystery of why there seem to be so many large galaxies in the early universe. After the dark matter “fuel” in their cores runs out, the regular matter that makes up most of the star collapses into a black hole, potentially providing the seeds for supermassive black holes. This could speed up the galaxy formation process. Other “too-early” galaxies might just be dark stars themselves, since they would look similar from this distance.
The astronomers on the new study identified the first three dark star candidates in Webb data. Three bright objects, designated JADES-GS-z13-0, JADES-GS-z12-0, and JADES-GS-z11-0, were discovered by Webb in December 2022 and assumed to be galaxies, but spectroscopic analysis indicates they have some of the expected properties of dark stars.
Of course, as fascinating as the idea may be, this study is extremely speculative. Not only do we not know if dark stars exist, but we don’t fully know if dark matter exists to power them in the first place. Even then, dark matter would have to exist in a specific form out of several proposed forms it could take. Occam’s razor is not on our side here.
“It’s more likely that something within the standard model needs tuning, because proposing something entirely new, as we did, is always less probable,” said Katherine Freese, co-author of the study. “But if some of these objects that look like early galaxies are actually dark stars, the simulations of galaxy formation agree better with observations.”
Thankfully, like any good hypothesis these dark stars are testable. Future observations from Webb could investigate certain properties, including dimming or excess intensity of light at certain frequency bands, which could help identify these objects.
The research was published in the journal PNAS.
Source: University of Texas at Austin
