ESA’s Euclid Finds 31 Ancient Quasars, Two From Universe’s First 670 Million Years
Thirty-one newly identified quasars have turned ESA’s Euclid space telescope into an unusually productive hunter of early supermassive black holes. The new Euclid results include two record holders whose light was emitted when the Universe was about 670 million years old roughly 5% of its current age.
The two objects, EUCL J172902.75+641018.1 and EUCL J125308.55+705432.3, have redshifts of 7.77 and 7.69, respectively. Both are now seen at distances of just over 13 billion light-years. That wording matters: Euclid did not observe the quasars billions of years ago. It collected ancient light that spent more than 13 billion years crossing space before reaching the telescope.
The larger result is not limited to two records. Twelve of the 31 quasars have redshifts of 7 or higher, placing their observed light within the Universe’s first 770 million years. ESA Research Fellow Antonio La Marca said the finding more than doubles the number of known quasars this ancient, converting what had been a collection of rare, unusually bright examples into a sample that can begin supporting population-level studies.
Why ancient quasars are difficult to find
A quasar is an intensely luminous galactic nucleus powered by material spiraling into a central supermassive black hole. During this active phase, the nucleus can outshine the rest of its host galaxy by hundreds or even thousands of times. That brightness makes quasars visible across enormous distances, but the earliest examples remain difficult targets.
They are intrinsically rare because relatively few galaxies had enough time to develop such systems during the Universe’s first several hundred million years. Their light is also faint by the time it reaches Earth and can be confused with light from much closer stars. Earlier searches consequently tended to recover the brightest outliers rather than a broader cross-section of the early quasar population.
Euclid addresses that search problem through a specific combination of survey scale and instrument design. Its 1.2-meter telescope sends incoming light to a visible-light camera and a near-infrared instrument. The visible camera supplies sharp, wide-field images, while the Near-Infrared Spectrometer and Photometer measures infrared light that has been stretched to longer wavelengths by the expansion of the Universe.
Neither sensitivity nor image sharpness alone solves the problem. A telescope must also survey enough sky to encounter objects that occur infrequently. Euclid’s Wide Survey is planned to cover more than one-third of the sky, allowing its processing system to sift a large observing area for faint candidates. The 31 quasars emerged from that survey rather than from a narrow observation aimed at one known object.
A larger sample changes the research
For decades, astronomers found only a handful of the brightest quasars from this period. Euclid’s sample provides a better basis for asking whether those luminous discoveries were representative or merely the easiest members of a much broader population to detect.
Follow-up work has already added context to one of the two oldest objects. Detailed observations placed it inside a dusty, gas-rich galaxy undergoing rapid star formation. That finding does not yet explain how early galaxies built enormous central black holes so quickly, but it connects black-hole activity with conditions inside at least one developing host galaxy.
The objects also come from the epoch of reionisation, a major transition during which energetic light transformed the neutral material filling the young Universe. Quasars can serve as bright background beacons for studying that period, while their host galaxies provide clues about how early black holes and stellar systems developed together.
Euclid launched in 2023 primarily to map the large-scale Universe and investigate dark matter and dark energy. Its quasar haul demonstrates the secondary value of building a space observatory around broad coverage, sharp imaging and infrared sensitivity. The mission has not solved the formation mystery, but it has changed the available sample: 31 new objects now stand where astronomers previously had only scattered bright outliers, and the Wide Survey still has most of its planned sky to cover.
By David Whitaker — Associate editor for AMI’s aerospace and drone systems desk, translating flight systems, aircraft programs, spaceflight, and UAV developments into accessible technical stories.
