The European Space Agency’s Euclid space telescope has identified 31 ancient quasars, including the two earliest ever observed, offering an unprecedented glimpse into the universe when it was only 670 million years old. Published in Astronomy and Astrophysics, the discovery dramatically expands astronomers’ view of the first generation of supermassive black holes and the galaxies that hosted them, opening a new chapter in the study of the early cosmos.
A New Window Into the Universe’s Earliest Giants
Quasars rank among the brightest objects in existence, powered by supermassive black holes consuming enormous amounts of gas at the centers of young galaxies. During this short-lived phase, the galactic core can outshine every star in its host galaxy by hundreds or even thousands of times. Finding these distant beacons has challenged astronomers for decades because the earliest examples are extraordinarily rare, faint, and easily confused with much closer stars. Euclid has now transformed that search.
The mission identified 31 previously unknown quasars dating back to the universe’s first billion years, including 12 with redshifts above 7, representing a period when the cosmos was still emerging from its earliest evolutionary stages. Among them are EUCL J172902.75+641018.1 with a redshift of 7.77 and EUCL J125308.55+705432.3 with a redshift of 7.69, now recognized as the oldest quasars ever discovered. Their light began its journey more than 13 billion years ago, reaching Earth after traveling across nearly the entire history of the universe.
“These early quasars date back to the universe’s infancy,” says Daming Yang of Leiden University in the Netherlands, lead author of the Euclid discovery paper. “By finding and studying them, we can better understand how these enormous systems formed and grew so quickly—one of the greatest mysteries in astrophysics.”
Euclid Changes the Search for Ancient Quasars
For many years, astronomers could detect only the brightest and rarest members of the ancient quasar population. Those exceptional objects offered valuable clues, yet they represented only a tiny fraction of what actually existed in the early universe. Euclid’s combination of wide-area imaging, deep infrared observations, and sharp space-based vision allows researchers to move beyond isolated discoveries and conduct large-scale surveys capable of revealing much fainter objects.
The mission is producing what scientists describe as the first meaningful census of primordial quasars rather than a collection of extraordinary exceptions. The findings, published in Astronomy and Astrophysics, demonstrate how powerful large-scale surveys have become for investigating the earliest stages of cosmic evolution. As Euclid continues scanning more than one-third of the sky during its mission, astronomers expect many more ancient quasars to emerge from its growing database.
“Euclid is a true game-changer,” adds Yang. “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. It’s a unique tool for quasar hunting.”
The Largest Census Yet of the Earliest Quasar Population
The scale of the discovery marks one of the most significant advances in early-universe astronomy in recent years. Building the original sample of roughly ten quasars with redshifts of 7 or higher required more than a decade of observations using multiple observatories around the world. Euclid has effectively surpassed that milestone within a single year, illustrating how dramatically observational capabilities have improved. Rather than simply adding new objects to an existing catalog, the mission is beginning to reveal the overall distribution of quasars during one of the universe’s formative eras. This larger sample enables astronomers to compare black hole growth, galaxy formation, and environmental conditions across multiple systems instead of relying on isolated examples. Such statistical studies are expected to reshape current models describing how supermassive black holes reached enormous masses so rapidly after the Big Bang.
“This finding more than doubles the number of quasars we know of that are so ancient,” says Antonio La Marca, an ESA research fellow on the Euclid team. Discovering the first 10 or so quasars at a redshift of 7 or above took astronomers more than a decade—but Euclid has already discovered more than that in a single year.
“The Euclid team has taken a true ‘census’ of quasars at the dawn of the universe for the first time,” adds La Marca. “It’s a big step toward understanding these fascinating objects on a more fundamental level.”
Clues to the Epoch That Shaped Today’s Universe
These newly identified quasars belong to the Epoch of Reionization, a transformational period when the universe evolved from the dark ages into one filled with ionized gas illuminated by the first generations of stars and galaxies. Scientists believe this era established the large-scale cosmic structures visible today, making every newly discovered quasar an invaluable probe of conditions at that time. Detailed follow-up observations of one of the newly found quasars have already revealed a dusty, gas-rich galaxy undergoing intense star formation, suggesting that massive black holes and vigorous galaxy growth occurred together remarkably early in cosmic history. Each additional observation will help determine how galaxies assembled, how black holes accumulated mass so efficiently, and how radiation from these energetic systems influenced their surroundings. As Euclid continues expanding its survey, researchers anticipate uncovering many more distant quasars capable of filling critical gaps in humanity’s understanding of the young universe.
“Ancient quasars are rare discoveries. They’re interesting in themselves, but also time machines that enable us to explore the early universe and understand how the first generation of galaxies came to be,” says Valeria Pettorino, ESA Euclid Project Scientist.
