Black holes with hundreds of millions of suns' mass when the universe was barely started
More than thirteen billion years ago, in a universe barely beginning to find itself, something vast and blazing already existed — supermassive black holes consuming matter on a scale that defies our understanding of how quickly the cosmos can build such things. An international team of astronomers, working with the Euclid space telescope, has now identified 31 of these ancient quasars, including the two oldest ever observed, their light only now completing a journey that began when the universe was a mere 670 million years old. The discovery does not simply add numbers to a catalog; it forces a reckoning with the foundational story we tell about how structure and gravity emerged from the early void.
- Supermassive black holes weighing hundreds of millions of solar masses have been found blazing in a universe so young it should not yet have had the time or material to build them.
- Detecting these objects is extraordinarily difficult — their light, stretched into infrared wavelengths by cosmic expansion, is nearly indistinguishable from ordinary foreground stars when viewed through Earth's atmosphere.
- Euclid, orbiting above that atmospheric interference, has in a single year more than doubled the known population of ancient quasars, a feat that took ground-based observatories decades to approach.
- Machine learning algorithms trained to sift through tens of millions of astronomical sources were essential to separating genuine quasars from the sea of stars that mimic their appearance in survey images.
- The team is now racing toward the first confirmed quasar beyond redshift 8 — a signal from within the universe's first 630 million years — while James Webb Space Telescope observations prepare to measure the masses and environments of these earliest giants.
The universe was barely 670 million years old when light from the first of these objects began its journey. That light has been traveling for just over 13 billion years, carrying news of something that strains our models of cosmic evolution: supermassive black holes, each hundreds of millions of times the mass of our sun, already blazing with the luminosity of a trillion suns in an infant cosmos.
An international team of astronomers has identified 31 of these ancient quasars using the Euclid space telescope, including the two oldest ever observed. Before Euclid launched in 2023, only a handful of such distant objects had been found over decades of searching. In a single year, the telescope more than doubled that count. Quasars are powered by supermassive black holes consuming vast quantities of matter, and their extreme brightness makes them cosmic lighthouses across time — but finding the oldest ones is extraordinarily hard. Their light, stretched by cosmic expansion from ultraviolet into near-infrared wavelengths, becomes nearly impossible to separate from foreground stars when viewed through Earth's atmosphere. Euclid, orbiting above that haze, can survey enormous areas of sky that ground-based telescopes cannot reach.
The two oldest quasars in the sample have redshifts of 7.69 and 7.77, placing them in the universe's first 670 million years. Physics professor Joseph Hennawi described the central puzzle plainly: finding black holes of such mass at a time when the universe was barely getting started challenges everything current theory predicts about how quickly gravity can accumulate matter. To find these objects, the team — led by doctoral student Daming Yang at Leiden University — built machine learning algorithms to search through tens of millions of astronomical sources, with two-thirds of the discoveries confirmed at the Keck telescopes in Hawaii.
One of the newly found quasars sits inside a dusty, gas-rich galaxy undergoing intense star formation, offering a rare window into what the earliest homes of supermassive black holes may have looked like. These objects all emerged during the epoch of reionization, when the first stars and galaxies ionized the neutral hydrogen that had filled space since the Big Bang — a transformation that laid the foundation for the universe we inhabit today.
The pace of discovery is accelerating sharply. It took more than a decade to find the first ten quasars with redshifts above 7; Euclid has surpassed that in one year. The team's next milestone is the first confirmed quasar beyond redshift 8, from within the universe's first 630 million years. Upcoming observations with the James Webb Space Telescope will measure black hole masses and study surrounding gas, while the Atacama Large Millimeter Array will examine dust and star formation in their host galaxies. Hennawi envisions assembling all of this into what he calls a quasar chronicle of the first billion years — a coherent account of how the universe's earliest and most improbable giants came to be.
The universe was barely 670 million years old when light from the first of these objects began its journey across space. That light has been traveling for just over 13 billion years to reach us now, carrying news of something that should not exist: supermassive black holes, each weighing hundreds of millions of times the mass of our sun, already blazing with the brightness of a trillion suns in an infant cosmos.
An international team of astronomers has now identified 31 of these ancient quasars using the Euclid space telescope, including the two oldest ever observed. The discovery, published in Astronomy & Astrophysics, represents a dramatic acceleration in humanity's ability to peer backward through time. Before Euclid launched in 2023, astronomers had managed to find only a handful of such distant objects over decades of searching. In a single year, the space telescope has more than doubled that count, revealing a population of early quasars that was previously invisible.
Quasars are among the brightest objects in existence—so luminous they can outshine entire galaxies. They are powered by supermassive black holes consuming vast amounts of matter, and their extreme distance and brightness make them cosmic lighthouses, allowing astronomers to see across more than 13 billion years of history. But finding the oldest ones is extraordinarily difficult. Quasars from the universe's first 770 million years are rare because few galaxies had grown large enough to produce them. Their light, stretched by the expansion of space from ultraviolet into near-infrared wavelengths—a phenomenon called redshift—becomes nearly impossible to distinguish from foreground stars when observed from Earth's surface. Ground-based telescopes struggle because these infrared wavelengths overlap with the natural glow of our own atmosphere.
Euclid orbits above that atmospheric haze, able to detect faint objects across enormous swaths of sky that terrestrial observatories cannot reach. The two oldest quasars in the new sample have redshifts of 7.69 and 7.77, meaning their light has traveled through space for 13 billion years, revealing them as they appeared during the universe's first 670 million years. Of the 31 newly discovered quasars, 14 have redshifts of 7 or higher. Joseph Hennawi, a physics professor with joint appointments at UC Santa Barbara and Leiden University, noted that these objects present a profound puzzle: "We're finding black holes with hundreds of millions of times the mass of our sun at a time when the universe was barely getting started."
The discovery raises a fundamental question about how the universe works. Current theories struggle to explain how such massive black holes could have formed so quickly. Hennawi and his colleagues, including lead author Daming Yang, a doctoral student at Leiden University, developed machine learning algorithms to sift through tens of millions of astronomical sources, identifying the genuine quasars hidden among countless stars that appear nearly identical in survey images. Two-thirds of the newly discovered quasars, including the three most distant, were confirmed using the Keck telescopes in Hawaii, where the University of California has privileged observing access.
One of the newly discovered quasars sits inside a dusty, gas-rich galaxy undergoing intense star formation, offering a rare glimpse of what the homes of the earliest supermassive black holes may have looked like. These objects emerged during the epoch of reionization, a pivotal era when the first stars and galaxies transformed the universe by ionizing the neutral hydrogen that filled space after the Big Bang. This period laid the foundation for the universe we see today.
The pace of discovery is accelerating. It took more than a decade to find the first 10 quasars with redshifts of 7 or greater. Euclid has already surpassed that in a single year. The team's next target is to discover the first quasar beyond a redshift of 8, which would reveal an object from within the universe's first 630 million years. Approved observing programs with the James Webb Space Telescope will measure the masses of these black holes and study the gas surrounding them. The Atacama Large Millimeter Array will examine the dust, gas, and star formation inside their host galaxies. Hennawi envisions stitching all of this together into what he calls "a quasar chronicle of the first billion years"—a coherent timeline of how the universe's earliest giants came to be.
Notable Quotes
These monsters—weighing billions of times the mass of our sun—somehow already existed when the universe was in its infancy. We don't yet have a good understanding of how they grew so massive, so fast.— Joseph Hennawi, UC Santa Barbara and Leiden University
Euclid is a true game-changer. Before, we could only find a handful of the very brightest ancient quasars, but Euclid lets us search far more efficiently across huge areas of sky to capture much fainter light.— Daming Yang, lead author and doctoral student at Leiden University
The Hearth Conversation Another angle on the story
Why does it matter that we found these particular quasars now, rather than five years ago?
Because we couldn't see them before. Euclid orbits above Earth's atmosphere, which blocks the infrared light these ancient objects emit. Ground-based telescopes were essentially blind to them. Now we can detect them across huge areas of sky, and we're finding them much faster than anyone expected.
But you said we already knew supermassive black holes existed in the early universe. What's new here?
We knew they existed, but only the brightest ones. We'd found a handful of exceptional cases. Now we're seeing a broader population—31 objects instead of a few. That changes everything about what we think the early universe looked like. It's the difference between knowing a few outliers and understanding the actual landscape.
The article mentions machine learning. How does that help find quasars?
When you survey millions of objects in the sky, most of them are stars in our own galaxy. A distant quasar looks almost identical to a nearby star in the images. Machine learning algorithms can process millions of sources and flag the ones that have the statistical fingerprint of a quasar—the right colors, the right brightness pattern. It's like finding a needle in a haystack by teaching a computer what needles look like.
These black holes are hundreds of millions of times the mass of the sun. How did they get so big so fast?
That's the real mystery. In the current models, black holes grow by consuming matter and merging with other black holes. But there wasn't enough time in the first 670 million years for that process to produce objects this massive. Either the black holes formed differently than we think, or they grew much faster, or both. These discoveries are forcing physicists back to the drawing board.
What happens next? Do we just keep looking for older and older quasars?
Partly, yes—the team wants to find the first quasar beyond a redshift of 8. But the real work is understanding what we've found. The James Webb Space Telescope will measure how massive these black holes actually are. Other instruments will study the galaxies around them, the gas, the dust, the star formation. The goal is to build a complete picture of how the early universe assembled itself.