The most powerful space telescope in Europe has just captured light that has been traveling for more than 13 billion years — revealing some of the earliest and most violent objects ever to exist in our universe.
Using data from ESA's Euclid space telescope, an international team of astronomers has identified 31 of the oldest quasars ever discovered. Two of them set new records: they formed when the universe was only about 670 million years old, just 5 percent of its current age. The findings were published this month in the journal Astronomy & Astrophysics.
What Makes These Quasars Special
Quasars are among the most luminous objects in the cosmos. Powered by supermassive black holes consuming vast amounts of surrounding material, they radiate extraordinary energy — sometimes equivalent to the combined output of a trillion suns. They're visible across almost incomprehensible distances, which makes them uniquely useful as probes of the early universe.
The 31 objects identified in the new study are exceptional even by quasar standards. "These objects provide the best clues for understanding how supermassive black holes form," said co-author Joseph Hennawi, a physics professor with joint appointments at UC Santa Barbara and Leiden University. "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."
Finding quasars from this early epoch has been extremely difficult. Their light is stretched by the expansion of the universe from ultraviolet into near-infrared wavelengths, making it hard to detect from Earth's surface. And because these objects are so rare, surveys need to cover enormous swaths of sky with extraordinary depth and precision.
Why Euclid Changes the Game
Enter Euclid. Launched in 2023 and operating above Earth's atmosphere, the telescope avoids the infrared glow that blurs ground-based observations. Its wide field of view allowed the team to survey vast areas of sky with the sensitivity needed to detect these faint, distant objects.
Lead author Daming Yang, a doctoral student at Leiden University, explained the challenge: "For every one of them there are thousands of stars in our Milky Way and nearby galaxies that look almost identical in the imaging surveys. And since their light is stretched to the infrared at such distances, we need a survey that is both wide enough to capture these rare objects and deep enough to detect their faint light."
The 31 newly identified quasars more than double the previously known number from this early cosmic era. Twelve of them date to within the universe's first 770 million years. The two oldest formed when the cosmos was less than 5 percent of its present age — and their light has taken more than 13 billion years to reach Earth.
What Comes Next
The discovery isn't just a record-breaking tally — it's a new dataset that scientists can now study in detail. Each of these quasars represents a supermassive black hole that grew to billions of solar masses with astonishing speed, a phenomenon that current theories of black hole formation struggle to explain. Were they seeded by unusually massive primordial clouds? Did they grow through rapid mergers? The answers may come from studying these objects in depth.
The Euclid mission is still in its early phases. As the telescope continues its survey over the next several years, researchers expect to discover many more of these ancient objects, providing an ever-richer picture of how the first galaxies and black holes assembled themselves in the universe's first billion years.
For astronomers, these 31 quasars are some of the oldest lighthouses in existence — their ancient light finally reaching us, carrying secrets from the very dawn of cosmic time.
