New paper suggests that the first stars of the universe were about as different from twinkling, sun-like stars as possible. These “dark stars,” he claims, were fueled by huge globs of annihilating dark matter and gave birth to the galaxies we see today.
Strange as they are, such stellar bodies explain one of astronomy’s newer mysteries.
In December 2022, James Webb Space Telescope identified three ancient galaxies as part of its JWST Advanced Deep Extragalactic Survey (JADES). These distant deep-redshift objects existed between 320 million and 400 million years after the Big Bang, making them among the earliest objects ever identified in the nascent universe. How did they form so quickly, given that the first stars are thought to have ignited not long before?
The new research suggests that these galactic ancestors were not galaxies at all.
“When we look at the James Webb data, there are two competing possibilities for these objects,” said Kathryn Freese, an astrophysicist at the University of Texas at Austin, in declaration. “One is that they are galaxies containing millions of ordinary population III stars. The other is that they are dark stars.
A dark star is a bloated concentration of dark matter colliding with itself and producing light and heat through annihilations. In the early universe, clouds of hydrogen and helium would have cooled and contracted around these concentrations, heating them further. The greater the concentration, the more frequent dark matter collisions.
“If some of these objects that look like early galaxies are actually dark stars,” Freese said, “the galaxy formation simulations agree better with the observations.”
The best fuel?
The true nature of dark matter is one of the great unsolved questions in all of physics. Scientists believe it is a new type of elementary particle, like a A weakly interacting massive particle (WIMP), although current efforts to detect one have come up empty. With 85 percent of the matter in the known universe, the potential for dark matter to have powered massive stars in the past is high.
“Believe it or not, a dark star has enough light to compete with an entire galaxy of stars,” Freese said. In theory, a dark star can burn up to 10 billion times brighter than the sun.
What’s more, Friese and colleagues have suggested that as dark stars formed the centers of protogalaxies, they spawned the newer galaxies we see all around us. How did this happen? When dark stars ran out of dark matter fuel, they collapsed into black holes, which spawned the supermassive black holes now found at the center of many galaxies.
Learning from the dark stars
Dark matter detectors around the world hope to detect one of the theorized particles, while observations of dark matter stars could reveal a lot about the mysterious substance. The researchers hope to revisit the three “galaxies” suspected of being dark stars to take a closer look at their spectroscopic properties. With more data, they could confirm the existence of the exotic stars.
“Confirmation that even one of these objects is a dark star would mark a new era in astronomy,” the paper said.