How dark stars could solve a huge cosmological puzzle


IN THE early days – and we are talking very early, not long after the big bang – the universe might have been littered with strange stellar monsters. Wide enough to engulf our whole solar system, these stars would be powered not by nuclear fusion, like a regular star, but instead by dark matter: specifically, particles of this mysterious stuff self-annihilating to fuel so-called “dark stars”.

That is the idea, at least. But when Katherine Freese, a theoretical astrophysicist at the University of Texas at Austin, first presented it at a conference in 2007, it didn’t go down particularly well. “I overheard some graduate students calling us crackpots,” she says.

Regardless, the concept of dark stars has stuck with Freese. Over the past 16 years, she and her colleagues have refined their understanding of these tantalising hypothetical objects. The problem was, finding evidence for them always seemed out of reach.

Until recently, that is, because Freese and her colleagues have reported a potential sighting: unusual galaxies seen by a new telescope. “Maybe some of these objects aren’t really galaxies at all, but actually singular stars – dark stars,” says team member Jillian Paulin, then at Colgate University in New York.

Echoes of doubt still sound among other astronomers. “It’s a very controversial idea,” says Cosmin Ilie, also at Colgate University, who led the team. But if they do exist, dark stars would not only be evidence for a specific kind of dark matter. They could also help crack one of the biggest problems in cosmology – the mysterious origins of the supermassive black holes that drive galactic evolution.

Our universe is awash with dark …


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