Full Breakdown
Euclid Discovers Record-Breaking Sample of Ancient Quasars
7/10/2026, 6:36:27 PM
Core Discovery
The European Space Agency’s Euclid space telescope has identified 31 quasars that existed when the universe was only about 5 % of its current age—roughly 670 million years after the Big Bang. Among them, two objects—EUCL J172902.75+641018.1 (redshift 7.77) and EUCL J125308.55+705432.3 (redshift 7.69)—are the earliest quasars ever documented, shining with a luminosity ? 1 trillion times that of the Sun and lying > 13 billion light-years from Earth.
Background & Context
Quasars are the intensely luminous cores of galaxies powered by supermassive black holes that accrete surrounding gas and dust. Their light outshines the host galaxy, making them visible across vast cosmic distances. The epoch of reionization (? 680 Myr – 1.1 Gyr after the Big Bang) marks the transition from a neutral-hydrogen “fog” to a transparent universe, and quasars from this era serve as probes of that transformation. Prior to Euclid, only a handful of quasars with redshifts > 7 had been found over more than a decade of observations.
Key Researchers & Institutions
- Daming Yang, doctoral researcher, Leiden University (lead author)
- Joseph Hennawi, astrophysicist, University of California, Santa Barbara & Leiden University (co-author)
- Antonio La Marca, ESA research fellow on the Euclid team
- Valeria Pettorino, ESA Euclid project scientist
- The Euclid Consortium (thousands of scientists and engineers) and ground-based follow-up teams at the Keck Observatory, Hawaii, Chile, and Arizona.
Data & Statistics
- 31 quasars discovered in Euclid’s Wide Survey (? 1/3 of the sky).
- 12 of them date to the first 770 Myr of cosmic history.
- 21 have been spectroscopically confirmed by ground-based telescopes.
- The two record-setting quasars have redshifts 7.77 and 7.69, placing them ? 13 billion light-years away.
- Their brightness is ? 10¹² L? (solar luminosities).
- This haul more than doubles the number of known quasars from the universe’s first billion years.
Why It Matters
The existence of such massive black holes so early challenges current models of black-hole formation and growth, which struggle to produce billion-solar-mass objects within a few hundred million years. The enlarged sample enables statistical studies of black-hole masses, accretion rates, and host-galaxy environments, and provides numerous “backlights” to map the ionization state of intergalactic hydrogen during reionization.
Official Statements & Responses
Researchers emphasize that Euclid’s infrared capability and wide-area coverage have transformed the field, allowing detection of fainter, more typical quasars rather than only the brightest outliers. The findings are presented as a “census” of early quasars, opening a path to weigh black-hole masses with upcoming James Webb Space Telescope observations and to probe the surrounding gas and dust.
Criticism & Open Questions
While the discovery expands the known population, the masses of the two earliest black holes remain unmeasured, leaving the core puzzle of how they grew so rapidly unresolved. The community acknowledges that existing growth scenarios may require exotic formation channels or faster accretion than presently modeled.
Verbatim Quotes
- “A quasar is the blazing core of a galaxy,” — Daming Yang, doctoral student, Leiden University
- “The most important thing these distant quasars tell us is that these supermassive black holes were already present in the extremely early cosmic times. This does not provide very much time to grow these objects, because the universe is simply too young. This is a major unsolved problem in astrophysics,” — Joseph Hennawi, astrophysicist, UC Santa Barbara & Leiden University
- “This finding more than doubles the number of quasars we know of that are so ancient,” — Antonio La Marca, ESA research fellow
- “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,” — Valeria Pettorino, ESA Euclid project scientist
- “Euclid removes this barrier entirely. It scans the sky in the infrared from space, with a speed and depth no ground-based survey can approach, and that is the core engine of this leap.” — Da-Ming Yang, Leiden University
What’s Next
The team has secured James Webb Space Telescope time to measure black-hole masses and investigate the gas and dust in host galaxies. Continued Euclid observations will expand the sky coverage, likely revealing still earlier quasars and further refining the timeline of cosmic reionization.
