Astronomers may have detected the first signs of dark stars, powered by dark matter annihilation rather than nuclear fusion, in observations from the James Webb Space Telescope. These objects could explain enigmatic early universe features like supermassive black holes, little red dots, and blue monsters. Researchers suggest they form seeds for massive black holes and offer clues to dark matter's nature.
In the dense conditions of the early universe, dark stars could emerge when gas clouds collapse with sufficient dark matter, leading to annihilation that powers the star before nuclear fusion begins. This process allows dark stars to grow massively without collapsing prematurely, unlike ordinary stars that fuse heavier elements until exhausting fuel and forming black holes.
A team led by Katherine Freese at the University of Texas at Austin modeled the evolution of these stars. They calculated that dark stars reach instability between 1,000 and 10 million solar masses, at which point general relativity causes collapse into black holes. George Fuller at the University of California, San Diego, explained: “You can take an ordinary, solar-mass sort of star, put some dark matter into it so the power source for that star is not nuclear reactions but dark matter annihilation, and you can keep feeding it. As long as you keep feeding it with enough dark matter too, it’ll never go through the nuclear evolution that gets it in trouble.”
This mechanism addresses the puzzle of supermassive black holes observed mere hundreds of millions of years after the Big Bang. Freese noted: “If you have a black hole of 100 solar masses, how the hell are you going to get up to 1 billion solar masses in a few hundred million years? It’s just not possible if you’re only making black holes from standard stars.” Dark stars could provide the large seeds needed for rapid growth.
James Webb Space Telescope data on distant little red dots and blue monsters, initially thought to be compact galaxies, also align with dark star characteristics. Freese's group found tentative spectral absorption hints at wavelengths too cool for normal stars or galaxies. However, Freese cautioned: “Right now, all the candidates that we have, there are two things that could fit the spectra equally well: one supermassive dark star or an entire galaxy of regular stars.”
Dan Hooper at the University of Wisconsin-Madison described the evidence as “a really well-motivated thing that they’re looking for,” though not definitive. Confirming dark stars, per Volodymyr Takhistov at Japan's High Energy Accelerator Research Organization, would reveal dark matter properties, especially if they seed black holes, as collapse mass depends on dark matter particle size. More precise JWST observations are needed to distinguish them from galaxies.