Astronomers ponder early origins of mysterious ‘red monster’ galaxy

Astronomers ponder early origins of mysterious ‘red monster’ galaxy

Researchers are perplexed by a galaxy that seems too big and too dusty for its place in cosmic history, less than half a billion years after the big bang.

By Jenna Ahart edited by Lee Billings

Astronomers studying the early universe with NASA’s James Webb Space Telescope (JWST) have discovered what appears to be a time traveler from the future: a large galaxy so filled with dust that the light from its abundant blue stars has taken on a crimson hue. Such heavy dust loads are generally thought to appear much later in cosmic history than about 400 million years after the Big Bang, when this new galaxy appeared.

Although the work has not yet been peer-reviewed, a pre-printed study who analyzed this “red monster” galaxy, officially called EGS-z11-R0, is already making waves in the astronomy community. “It’s amazing how short these time frames are,” says Pieter van Dokkum, an astrophysicist at Yale University who was not involved in the study. “Sharks and turtles have been around about as long.”

For perspective, seeing a galaxy this large and dusty less than half a billion years into the 13.8 billion year history of the universe is a bit like finding a redwood tree towering over its saplings in a recently plowed field; it’s difficult to explain how something so giant reached maturity so quickly, in the blink of a cosmic eye. Clues could come from studying other hidden giants in the galactic neighborhood – “blue monster” galaxies, also discovered by JWST but lacking the red-inducing dust buildup. (Red monsters should not be confused with “Red Monsters”little red dots“, a totally different but no less mysterious type of object that the observatory spied in the early universe and is now thought to indicate supermassive black holes still forming.)

On supporting science journalism

If you enjoy this article, please consider supporting our award-winning journalism by subscribe. By purchasing a subscription, you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

Giulia Rodighiero, lead author of the study and an astronomer at the University of Padua in Italy, wondered whether other large objects, perhaps obscured by their own dust, might reside among the JWST’s blue monsters. So she and her colleagues scoured the Dawn JWST archives, a repository of public data on JWST galaxies, looking for potential suitors. EGS-z11-R0 was the only clear candidate that emerged.

The telltale signature of abundant dust lies in the galaxy’s ultraviolet light continuum, which has a relatively flat slope due to absorption by dust. Rodighiero notes that while the researchers’ analysis indicates that the reddening effect comes primarily from dust, they are still looking for more direct evidence, because light emanating from ionized gas clusters in the galaxy may also be involved. By obtaining a spectrum of EGS-z11-R0, that is, collecting and analyzing its light into constituent colors or wavelengths, the team also found evidence for the presence of carbon as another sign of galactic maturity. “There’s a whole cycle that has to happen before you get to a heavily dust-obscured red galaxy like this,” says van Dokkum. “It’s surprising that this happened so quickly and so early.” The study is a “tour de force” for extracting such indicative signatures, he adds.

The new red monster is just one of a growing group, with others typically spotted around a billion years after the big bang. Such galaxies had already surprised astronomers because of their surprising maturity. But with its location only 400 million years ago in the history of the universe, the new monster is something of an anomaly among anomalies. Yet JWST’s careful gaze can return to even further into the past. So far, the telescope has managed to spot galaxies around 280 million years after the Big Bang. This new discovery, however, seems to push back the first epochs of galaxy formation in the universe even further than astronomers had imagined. Given the time it takes for stars to produce such atoms and dust, van Dokkum says, the existence of EGS-z11-R0 suggests that astronomers could spot galaxies as early as 200 million years after the big bang.

As the new class of ancient red monsters emerges, some key questions also arise: How does dust accumulate so quickly, and why do only some galaxies have it? Finding answers will likely involve gathering a larger sample of these early-appearing red monsters, as well as observing them through different instruments aboard JWST, capable of detecting shorter and longer infrared wavelengths, says Callum Donnan, an expert on galactic evolution at the National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory, who was not involved in the study.

Rodighiero and his team already have suspicions about how red and blue monsters can coexist in the early universe. Perhaps blue galaxies were actually born from red galaxies as the dust dispersed. “We think they are linked by the same evolutionary history,” she says. “It’s just that we capture galaxies in different periods, and it is much easier to detect a blue monster.” She and her team hope that discovering more objects could help astronomers understand these galactic phases, and they also plan to examine a wider range of infrared light to fully confirm that EGS-z11-R0’s redness comes from its dust.