Euclid telescope finds 31 ancient quasars, setting cosmic distance record

The European Space Agency's Euclid space telescope has discovered 31 of the most ancient quasars ever observed, including two objects that set a new distance record for their kind, the agency said.

The two record-breaking galaxy cores, named EUCL J172902.75+641018.1 and EUCL J125308.55+705432.3, were already shining with the light of a trillion Suns when the universe was only about 670 million years old — roughly 5 percent of its current age, according to ESA and researchers at Leiden University in the Netherlands. Both sit more than 13 billion light-years from Earth.

What quasars are

Quasars mark a brief phase in a galaxy's life when large amounts of gas and other material spiral into a central supermassive black hole, releasing enormous energy. During this phase, the galactic nucleus can outshine the rest of its host galaxy by hundreds to thousands of times, making quasars the brightest objects in the cosmos.

Astronomers have hunted for the universe's earliest quasars for decades because they offer clues about how the first supermassive black holes and galaxies formed. Such objects are hard to find: few galaxies had grown large enough that early on, their primordial light is faint, and it is easily confused with light from nearer stars.

"These early quasars date back to the Universe's infancy," said Daming Yang of Leiden University, 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."

Filling in the picture

Until now, researchers said, known early quasars were mostly the rare, bright outliers that were easiest to spot, leaving the broader population poorly understood. Euclid, launched in 2023 and designed to survey huge areas of sky, is capturing fainter examples as well.

"Euclid is a true game-changer," Yang said. "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."

The discovery adds 12 new quasars with a redshift of 7 or higher — a measure of distance indicating they shone when the universe was at most about 770 million years old. The two record-breakers have redshifts of 7.77 and 7.69.

The quasars date to the reionization era, when radiation from the first stars transformed the universe from a cold, dark place into one whose hydrogen gas became ionized and transparent to ultraviolet light. Researchers say the objects could help reveal how quickly the first galaxies reshaped their surroundings.