JWST Findings Suggest Dark-Star Candidates in the Early Universe
New analyses of data from the James Webb Space Telescope (JWST) point to a striking possibility: some of the first stars in the universe may have been supermassive dark stars—giant, puffed clouds of hydrogen and helium whose light is powered not by fusion, but by tiny amounts of self-annihilating dark matter. A team led by Cosmin Ilie of Colgate University, with collaborators including Shafaat Mahmud, Jillian Paulin, and Katherine Freese, have identified four extremely distant objects whose spectra and shapes are consistent with this exotic class of stars.
Dark stars, as theorized, sit in the right conditions about a few hundred million years after the Big Bang, at the centers of dark matter halos. Their remarkable brightness and large sizes could be sustained by the heat produced as dark matter particles annihilate each other, offering an alternative path to the unusually bright yet compact galaxies JWST has begun to reveal and possibly to the seeds of the supermassive black holes seen in the most distant quasars.
What Are Supermassive Dark Stars?
Unlike ordinary stars that shine through nuclear fusion in their cores, supermassive dark stars are theorized to be powered, at least in part, by the heat from dark matter annihilation. They would be enormous—millions of solar masses—yet relatively diffuse or “puffy,” with a structure that balances gravity with the energy produced by dark matter. The idea, introduced in the late 2000s, links the presence of dark matter to the early growth of the first luminous objects and, ultimately, to the rapid emergence of black holes that power distant quasars.
The research builds on a thread dating back to Freese, along with Doug Spolyar and Paolo Gondolo, and later work showing how dark stars could grow to immense sizes and leave behind massive black hole remnants. While dark matter remains elusive in terrestrial experiments, its fingerprints, if present in early stars, could become accessible through JWST’s infrared spectroscopic capabilities.
New JWST Clues About Four Distant Objects
The team studied four of the most distant JWST targets with spectroscopy from the NIRSpec instrument: JADES-GS-z14-0, JADES-GS-z14-1, JADES-GS-z13-0, and JADES-GS-z11-0. Four objects, including two candidates from a 2023 photometric study, now show properties that can be modeled as supermassive dark stars powering compact nebulae of ionized hydrogen and helium. One object, z14-1, is unresolved and appears consistent with a single point source, while the others are highly compact and can be represented as a dark star embedded in surrounding gas.
A potential “smoking gun” feature for dark stars is an absorption dip at 1640 Angstroms caused by abundant singly ionized helium in the star’s atmosphere. In the new analysis, one of the four objects — JADES-GS-z14-0 — shows this 1640 Å feature, albeit at modest signal-to-noise (S/N of about 2). This would be the first spectroscopic hint of a dark-star signature in JWST data, a tantalizing clue in a field where conclusive confirmation is challenging.
Cross-checks and Complications
Even with the 1640 Å hint, the interpretation is not unique. The same four objects can also be modeled as distant galaxies, and independent measurements are needed for a definitive verdict. Moreover, data from the Atacama Large Millimeter/submillimeter Array (ALMA) revealing oxygen emission in the same object suggests the presence of metal-rich gas, which could indicate a merger scenario or a shared environment where dark stars and regular stars formed within the same halo. If confirmed, such a merger or coeval star formation could explain how a dark star sits inside a glowing nebula rather than existing in isolation.
Why This Matters: Dark Matter and Black Hole Seeds
The potential discovery of supermassive dark stars has far-reaching implications. If dark matter annihilation powers these stars, the observed properties offer a direct, astrophysical handle on the nature of dark matter—perhaps shedding light on particle candidates like weakly interacting massive particles (WIMPs). More broadly, supermassive dark stars could serve as the missing link between the first luminous objects and the rapid growth of supermassive black holes that power the most distant quasars, a longstanding puzzle in cosmology.
The Road Ahead
Researchers acknowledge that more data are needed to secure a dark-star interpretation. Future JWST spectra with higher signal-to-noise, extended wavelength coverage, and additional multi-wavelength observations will help determine whether these four objects are truly isolated dark stars, dark stars in nebulae, or conventional galaxies with unusual properties. If a consistent set of dark-star signatures emerges across more targets, astronomers will have opened a new frontier in the study of dark matter-powered stellar evolution.
Acknowledgments
As with many frontier discoveries, this work rests on a broad foundation of prior theory and observations. The researchers acknowledge support from Colgate University, the Picker Interdisciplinary Sciences Institute, the U.S. Department of Energy, the Swedish Research Council, the LSST Discovery Alliance, the Brinson Foundation, the WoodNext Foundation, and the Research Corporation for Science Advancement.
