The James Webb Space Telescope's deepest spectrum of one of the early universe's "little red dots" (small, intensely red objects catalogued since 2022) points to a "black hole star," a supermassive black hole wrapped in dense gas, and gives astronomers a repeatable way to study…
A faint red smudge in a James Webb Space Telescope image of the galaxy cluster Abell S1063 looked at first like one of hundreds of similar specks that have been turning up in deep surveys of the early universe. Magnified by the gravity of that foreground cluster, the smudge is in fact an object called GLIMPSE-17775, and it has just become the most informative spectrum ever recorded of one of the early universe's "little red dots." The data point toward a supermassive black hole hidden inside a thick gas shroud rather than a young galaxy full of new stars (Universe Today).
The cluster doing the magnifying is Abell S1063, a massive collection of galaxies whose gravity bends and amplifies the light of objects behind it. That effect, known as gravitational lensing, turned a planned 30-hour Webb exposure into something closer to 80 hours of usable signal, enough to pull 40 or more emission and absorption lines out of a single faint source. Earlier spectra of the little red dots had typically yielded a handful of features at best. The new dataset is the first time the field has had this kind of resolution on a single lensed member of the population (Universe Today).
Little red dots are exactly what the nickname promises. They are compact, intensely red, and surprisingly common, showing up about 600 million years after the Big Bang, far more often than models of early galaxy growth predicted. Some shine so brightly that the researchers who first catalogued them "half joked they had broken our understanding of how galaxies grow." The two main competing explanations have been either compact, dusty bursts of star formation, where reddened light comes from interstellar dust, or alternatively, growing supermassive black holes (Universe Today).
The pattern in the new spectrum fits what astronomers are calling a "black hole star," a coined term for a growing supermassive black hole whose ferocious light is reprocessed into a softer red glow by a thick surrounding envelope of gas, so that from a great distance the object looks almost starlike. The signature is consistent with a shrouded black hole rather than a dusty young galaxy. It is a narrower claim than "all little red dots are black holes," and it leaves room for rival geometries, including some active galactic nuclei models, to be tested against the same kind of data (Universe Today).
The bigger story is the method. Gravitational lensing by Abell S1063 turned one faint dot into a usable target, and the same trick can be applied to other lensed little red dots scattered across the sky. Each new lensed target is a chance to stack spectra, test the shrouded-black-hole picture against the dusty-starburst picture, and begin to put numbers on how often the universe grew its earliest supermassive black holes inside these red disguises. The next few years of Webb time are likely to be spent on exactly that kind of comparison, with GLIMPSE-17775 as the first clear benchmark rather than the last word.