James Webb Space Telescope detects ‘little red dots’: What are black hole stars

Astronomers theorise that they are early galaxies that existed earlier than 700 million years after the Big Bang.

Performing an analysis of the little red dots, the researchers suggested that, rather than being ancient, well-developed galaxies, little red dots may be vast spheres of dense and hot gas that look like the atmospheres of stars. (Image: Penn State University)

New research suggests that “little red dots” seen in the early universe may actually be a new class of cosmic object: black hole stars. If this theory is correct, it could explain how black holes managed to grow to supermassive sizes before the universe was even 1 billion years old.

These little red dots are one of the most curious celestial objects viewed thus far by the James Webb Space Telescope (JWST). Astronomers theorise that they are early galaxies that existed earlier than 700 million years after the Big Bang, unlike anything seen in the local and “modern” 13.8 billion-year-old universe.

If these objects truly are galaxies, they are remarkably well-developed for their age. Packed with mature, red stars, the existence of these “little red dots” so soon after the Big Bang has been a cosmic puzzle. Their very presence challenges our understanding of how galaxies form and evolve, earning them the nickname “universe breakers” among some scientists. But new research could be the solution, suggesting that these red dots are not galaxies at all, but rather a completely new class of cosmic object. This theory could mend our broken understanding of the early universe.

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Performing an analysis of the little red dots, the researchers suggested that, rather than being ancient, well-developed galaxies, little red dots may be vast spheres of dense and hot gas that look like the atmospheres of stars. However, rather than being powered by nuclear fusion, like stars are, the engines of these objects are supermassive black holes greedily feeding on surrounding matter and blasting out energy.

The theory could explain why little red dots appear more massive and much brighter than galaxy formation models suggest. To be so bright, a galaxy would have to be loaded with stars at an impossible density. Princeton University researcher Bingjie Wang said that the night sky of such a galaxy would be dazzlingly bright, implying that stars formed through extraordinary processes that have never been observed before.

In July 2024, Penn State University researcher Joel Leja and colleagues examined light from these objects at different wavelengths, or spectra, throughout 2024. The team realised that the Cliff, located around 12 billion light-years from Earth, was exactly the sort of object they needed to investigate the nature of the JWST’s little red dots. The mass increase of feeding black holes like the one seen as the Cliff is “turbo-charged,” meaning these new black hole stars could help to explain the growth of supermassive black holes.

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