Photo: Bangzheng "Tom" Sun
Astronomers using the James Webb Space Telescope may have moved closer to solving the mystery of the so-called "little red dots" after discovering that many of them appear to have nearby "little blue companions," according to a new study reported by Live Science.
Little red dots are compact, unusually bright objects that appeared roughly 600 million years after the Big Bang, when the universe was less than 10% of its current age, before disappearing about a billion years later.
Researchers analyzed 83 little red dots identified in James Webb's deep-field observations and found that 36 of them—including more than 80% of the brightest examples—had at least one nearby companion emitting intense blue ultraviolet light.
The newly identified companions are estimated to contain between hundreds of millions and billions of solar masses, suggesting they could be dense star clusters or relatively small early galaxies.
The research team proposes that intense ultraviolet radiation from these companions may have prevented giant gas clouds from fragmenting into ordinary stars. Instead, the clouds may have collapsed into supermassive stars that rapidly turned into black holes, bypassing the usual supernova stage.
"We think what we call the 'companions' is starlight," said lead author Josephine Baggen, an astronomer at Yale University.
The hypothesis could also explain the unusual light signatures of little red dots. According to the researchers, the red optical light comes from the little red dot itself, while the ultraviolet emission originates from its nearby companion. The gap between the two is likely caused by dense hydrogen gas surrounding the red object, which absorbs specific wavelengths of light.
If confirmed, the findings could provide new insight into how some of the universe's earliest black holes formed.
