Observations from the James Webb Space Telescope suggest that the universe's earliest stars may have been supermassive dark stars powered by dark matter annihilation rather than nuclear fusion. A new study identifies four distant objects matching this description, potentially explaining bright early galaxies and supermassive black holes. These findings build on theories proposed over a decade ago.
In the early universe, about 300 million years after the Big Bang, the first stars formed from clouds of hydrogen and helium. A study published in the Proceedings of the National Academy of Sciences on October 14, 2025, led by Cosmin Ilie of Colgate University, along with Shafaat Mahmud, Jillian Paulin, and Katherine Freese, analyzed JWST data to identify four candidates for supermassive dark stars.
These objects—JADES-GS-z14-0, JADES-GS-z14-1, JADES-GS-z13-0, and JADES-GS-z11-0—at redshifts up to 14, exhibit spectral signatures consistent with supermassive dark stars. "Supermassive dark stars are extremely bright, giant, yet puffy clouds made primarily out of hydrogen and helium, which are supported against gravitational collapse by the minute amounts of self-annihilating dark matter inside them," Ilie explained.
The concept originated in a 2008 Physical Review Letters paper by Freese, Doug Spolyar, and Paolo Gondolo, with expansions in 2010 detailing how such stars could grow massive and collapse into supermassive black holes. A 2023 PNAS study had previously flagged candidates using photometric data; now, spectroscopic analysis with JWST's NIRSpec confirms compatibility.
Freese, director of the Weinberg Institute at UT Austin, noted: "For the first time we have identified spectroscopic supermassive dark star candidates in JWST, including the earliest objects at redshift 14, only 300 Myr after the Big Bang. Weighing a million times as much as the Sun, such early dark stars are important not only in teaching us about dark matter but also as precursors to the early supermassive black holes seen in JWST."
A key feature is an absorption line at 1640 Angstroms from ionized helium, observed in JADES-GS-z14-0 with a signal-to-noise ratio of about 2. Ilie described this as a "smoking gun signature." ALMA observations of the same object detected oxygen emission, suggesting a metal-rich environment, possibly from a merger or co-formation with regular stars.
These dark stars, powered by Weakly Interacting Massive Particles (WIMPs) annihilating in dark matter halos, could resolve puzzles like unexpectedly bright early galaxies and the origins of distant quasars' black holes.