The first stars in the universe formed out of pristine hydrogen and helium clouds, in the first few hundred million years after the Big Bang. New James Webb Space Telescope (JWST) observations reveal that some of the first stars in the universe could have been very different from regular (nuclear fusion-powered) stars, which have been observed and cataloged by astronomers for millennia.

A recent study led by Cosmin Ilie, at Colgate University, in collaboration with Shafaat Mahmud, Jillian Paulin at UPenn, and Katherine Freese, at The University of Texas at Austin, identifies four extremely distant objects which are consistent, both from the point of view of their observed spectra and morphology, with being supermassive dark stars. The paper is published in the journal Proceedings of the National Academy of Sciences.

"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 said.

Supermassive dark stars and their black hole remnants could be key to solving two recent astronomical puzzles: the larger than expected extremely bright, yet compact, very distant galaxies observed with JWST, and the origin of the supermassive black holes powering the most distant quasars observed.

Freese developed the original theory behind dark stars with Doug Spolyar and Paolo Gondolo. They published their first paper on this theory in the journal Physical Review Letters in 2008. In that paper, they envisioned how such dark stars might have led to supermassive black holes in the early universe. In a 2010 Astrophysical Journal publication, Freese, Ilie, Spolyar, and collaborators identified two mechanisms via which dark stars can grow to become supermassive, and predicted that they could seed the supermassive black holes powering many of the most distant quasars in the universe.

Although dark matter makes up about 25% of the universe, its nature has eluded scientists. It is now widely believed that dark matter consists of a new type of elementary particle, yet to be observed or detected. While the hunt to detect such particles has been on for a few decades, no conclusive evidence has been found yet. Among the leading candidates for dark matter are Weakly Interacting Massive Particles. When they collide, these particles would theoretically annihilate themselves, depositing heat into collapsing clouds of hydrogen and converting them into brightly shining dark stars.

The conditions for the formation of dark stars were just right a few hundred million years after the Big Bang, and at the center of dark matter halos. This is when and where the first stars in the universe are expected to have formed.