Imagine standing at the edge of time, less than a billion years after the Big Bang, when the universe was still in its infancy. Galaxies were only beginning to take shape, stars were burning furiously, and the cosmos was glowing with youthful energy. It was a period astronomers call the Cosmic Dawn—an era that still holds some of the greatest mysteries about how our universe came to be.
Now, a groundbreaking discovery has pulled back part of that cosmic veil. Astronomers, using the combined power of the Subaru Telescope in Hawaii and the James Webb Space Telescope (JWST), have found hidden titans: supermassive black holes cloaked in thick dust, shining as brilliant quasars that had previously escaped detection.
This finding doesn’t just add to our list of cosmic curiosities. It challenges what we thought we knew about the early universe, suggesting that these voracious giants were more common, more active, and more influential than we ever imagined.
What Lies at the Heart of Galaxies
In today’s universe, nearly every galaxy hides a supermassive black hole at its core—objects millions to billions of times more massive than our sun. Most lie dormant, invisible and quiet. But when one of these black holes begins feeding on gas and stars, it unleashes a torrent of energy. This blazing spectacle is what astronomers call a quasar.
Quasars are so bright that they can outshine their entire host galaxy. They are cosmic beacons, visible across unimaginable distances, carrying information about times long past. Yet paradoxically, their light can also destroy the very environment that feeds them, blowing away the gas needed for stars to form. In this way, quasars don’t just live inside galaxies—they shape them.
The great puzzle has always been how these supermassive black holes appeared so quickly after the Big Bang. Within the first billion years, many were already billions of times heavier than our sun. Such rapid growth defies easy explanation, and solving this mystery is key to understanding how galaxies—and the universe itself—evolved.
The Problem of the Missing Quasars
Astronomers have been searching the Cosmic Dawn for quasars for decades. The earliest quasars were first identified by their ultraviolet radiation, which reaches us as visible light after traveling across billions of years. This approach led to the discovery of hundreds of quasars. But something didn’t add up.
If black holes grew so quickly, there should have been far more quasars lighting up the early universe. Instead, the numbers found were surprisingly small. Where were the missing quasars?
The answer, it turns out, lay in the dust. Galaxies in the early universe were rich with gas and dust—the raw materials for star formation. But this dust also acted like a cosmic curtain, blocking ultraviolet light and hiding quasars from view. What if the brightest quasars were there all along, simply obscured by their dusty cocoons?
Peering Through the Dust
That suspicion guided astronomers to look again, this time with better tools. Using the Subaru Telescope’s Hyper Suprime-Cam, researchers identified galaxies that seemed unusually luminous. For years, these galaxies puzzled astronomers: they were too bright for ordinary galaxies but didn’t show the telltale emission lines of quasars. It was as though something powerful was hidden inside, just out of reach.
The launch of JWST in 2021 changed everything. Unlike previous telescopes, JWST was built to see in the infrared—a wavelength of light that can slip through dust where ultraviolet cannot. When the team aimed JWST’s NIRSpec spectrograph at these mysterious galaxies, the truth was revealed.
Seven of the eleven galaxies examined showed the unmistakable broad emission lines that signal a quasar. These were not ordinary galaxies after all. They were dust-shrouded supermassive black holes, blazing with the power of trillions of suns, yet dimmed by the very material surrounding them.
For the first time, astronomers had confirmed the existence of hidden quasars in the early universe.
Twice as Common, Twice as Mysterious
This revelation changes the numbers dramatically. If dust-obscured quasars are as common as unobscured ones, then the population of bright quasars at the Cosmic Dawn is at least double what was previously thought.
This means supermassive black holes were even more widespread and influential than we realized. Their feedback—blasting radiation and winds into their host galaxies—would have profoundly shaped how galaxies grew. It also intensifies the mystery of their origin: how could so many giant black holes form so quickly after the universe began?
Some scientists argue that they might have grown from the remnants of the very first stars, the so-called “Population III” stars. Others suggest they may have formed through the direct collapse of massive gas clouds. The truth remains uncertain, but each new discovery brings us closer to an answer.
A New Era of Cosmic Exploration
The discovery also highlights the synergy of modern astronomy. Subaru’s wide survey revealed the rare candidates, while JWST’s infrared vision unveiled their true nature. Together, they have created a roadmap for future discoveries.
Researchers now plan to dig deeper. With JWST, they can study the chemical fingerprints in the light of these quasars, learning about the environment around the black holes. With ALMA, the powerful radio telescope in Chile, they can probe the gas and dust of the host galaxies. Each observation will help unravel the story of how galaxies and black holes co-evolved at the dawn of time.
This is just the beginning. New JWST programs are already approved to expand the search, aiming to uncover not only the brightest hidden quasars but also the fainter ones that may vastly outnumber them. If successful, astronomers may finally be able to map the true population of supermassive black holes in the young universe.
The Human Side of Discovery
Behind the science lies a human story—a decade of persistence and curiosity. For years, astronomers suspected that hidden quasars might be lurking in the data. They held onto that question, waiting for the tools to prove it. JWST became the key to unlocking a mystery that had lingered for so long.
As Dr. Yoshiki Matsuoka of Ehime University, the study’s leader, explained: “This discovery was only possible with the unique combination of two powerful telescopes. The Subaru Telescope’s wide and sensitive survey allowed us to spot rare, luminous galaxies, and JWST was able to catch the faint infrared light from the hidden quasars. This shows how effective the approach of ‘Discover with Subaru, explore with James Webb’ can be.”
This kind of collaboration—human minds working together across nations and generations, supported by decades of technological innovation—is what makes astronomy a uniquely unifying science.
A Universe Still Full of Secrets
The discovery of dust-shrouded quasars is a reminder that the universe still holds secrets just beyond our vision. Each time we build a better telescope, each time we learn to see in a new wavelength, the cosmos surprises us.
It is humbling to realize that, even after centuries of astronomical study, we are still only scratching the surface of the universe’s story. Somewhere out there, beyond our current reach, more hidden giants are waiting to be found. They are relics of a time when everything was new, when the first galaxies struggled into being, and when the seeds of today’s universe were planted.
And perhaps, as we look deeper into the dust and darkness of the Cosmic Dawn, we are not just discovering the history of the universe—we are discovering the history of ourselves, for the atoms in our bodies were born from the same stars that lit that ancient sky.
More information: Yoshiki Matsuoka et al, SHELLQs. Bridging the Gap: JWST Unveils Obscured Quasars in the Most Luminous Galaxies at z > 6, The Astrophysical Journal (2025). DOI: 10.3847/1538-4357/addf4e
