We Might Have Found the First Star Made of Dark Matter

Astronomers have uncovered compelling evidence for the existence of Dark Stars—massive stars in the early universe that might be partly energized by dark matter. If confirmed, these hypothetical stars could shed light on the enigmatic large black holes observed in the early universe, although skepticism remains among some astronomers regarding these findings.

The concept of Dark Stars was proposed in 2007 by Katherine Freese and her colleagues at the University of Texas at Austin. They theorized that immense clouds of hydrogen and helium in the early universe could interact with dark matter, forming gigantic and stable stars. Absent dark matter, such vast gas clouds would collapse into black holes, but energy from decaying dark matter can counter this collapse, resulting in star-like entities even without the nuclear fusion typical of ordinary stars.

Until recently, evidence for these exotic objects from the early universe was scant, but in 2022, the James Webb Space Telescope (JWST) began discovering numerous bright, distant celestial objects. Freese and her team identified three galaxies that exhibited several characteristics predicted by Dark Star models, such as round shapes and similar luminosity, though detailed spectral data was absent to confirm their hypothesis definitively.

Now, with new spectral observations from JWST, Freese’s team believes they can match theoretical predictions of what Dark Stars should resemble, including two additional candidates. One of these potential candidates shows intriguing hints of specific helium characteristics—missing electrons—which, if validated, could serve as a distinct hallmark of a Dark Star. Freese remarks, “If it’s real, I don’t know how else to explain it using Dark Stars.” She cautions, however, that evidence is still limited.

Meanwhile, Daniel Whalen from the University of Portsmouth in the UK suggests that an alternative theory of ultra-massive protostars, which do not involve dark matter, might also explain the JWST findings. “They overlook considerable literature concerning the formation of ultra-massive protostars, some of which can produce signatures remarkably similar to the ones they present,” claims Whalen.

Freese, however, strongly disagrees, asserting that burning dark matter is the only feasible method for creating such massive stars. “There’s no alternative route,” she insists.

A complicating factor arises from separate observations of the objects studied by Freese’s team using the Atacama Large Millimeter Array (ALMA) in Chile, which indicated the presence of oxygen. This element is not associated with Dark Stars, suggesting these candidates might be hybrid stars. On the other hand, Whalen and his team interpret the presence of oxygen as a strong indicator that these objects cannot be Dark Stars, attributing their formation to conventional stars that exploded as supernovae.

Should Freese and her collaborators confirm that these objects are indeed Dark Stars, it could address significant challenges in understanding the universe. Current models posit that such black holes can only originate from extremely massive matter, which raises questions about their formation in the early universe.