Euclid telescope discovers oldest quasars ever observed

The European Space Agency's Euclid space telescope has discovered 31 previously unknown quasars in the early universe, including two that set a new record as the most ancient quasars ever observed in cosmic history. The findings, published on July 6 in Astronomy & Astrophysics, more than double the number of known quasars from the universe's first 770 million years and deepen an enduring mystery about how supermassive black holes grew so large so quickly after the Big Bang.phys+1

Pushing Back the Cosmic Frontier

The two record-breaking quasars, designated EUCL J172902.75+641018.1 and EUCL J125308.55+705432.3, have redshifts of 7.77 and 7.69, respectively — surpassing the previous record-holder discovered in 2021, which had a redshift of 7.64. Both objects lie more than 13 billion light-years away and emerged when the universe was roughly 670 million years old, just 5% of its current age.esa+1

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

A Census of the Cosmic Dawn

The discovery adds 12 new quasars at a redshift of 7 or above, corresponding to the universe's first 770 million years. Finding the first roughly 10 such quasars took astronomers more than a decade; Euclid matched that in a single year of survey observations.phys+1

"The Euclid team has taken a true 'census' of quasars at the dawn of the Universe for the first time," said Antonio La Marca, an ESA Research Fellow. "It's a big step towards understanding these fascinating objects on a more fundamental level."esa

The quasars date to the epoch of reionisation, a transitional period when the cosmos shifted from cold darkness to a state energized by light — a phase that set the conditions for all cosmic structure seen today. Follow-up observations by the Subaru Telescope and other ground-based facilities showed that one of the most distant quasars is embedded in a dusty, star-forming galaxy, offering clues about the environments surrounding early supermassive black holes.subarutelescope+1

Euclid's Unrivalled Reach

Euclid, launched in July 2023, combines wide-area sky coverage with deep infrared imaging from space — a combination that allows it to detect faint, distant objects far more efficiently than ground-based surveys. The 31 quasars were identified from the Euclid Wide Survey, which will ultimately cover more than one-third of the sky.dw+1

"Euclid's capabilities are unrivalled," said ESA Euclid Project Scientist Valeria Pettorino. "The telescope combines a large area, depth, sharp imaging, and unique space-based infrared vision in a way that lets us pick out rare, extremely distant objects far more efficiently than before."esa