Thirty-one ancient quasars shining with the power of a trillion suns have been discovered by the European Space Agency’s Euclid space telescope, including two that set new records as the earliest ever observed.
As noted by ScienceDaily, when the cosmos was merely 670 million years old—roughly 5% of its current duration—these dazzling galactic cores, driven by massive black holes, already emitted light equal to a trillion suns.
Quasars emerge during a relatively brief phase of a galaxy’s evolution when massive amounts of gas and other matter plunge toward its central supermassive black hole. This mechanism generates massive bursts of energy, making the galaxy’s center glow hundreds or even thousands of times brighter than the rest of the galaxy combined.
For decades, researchers have hunted for quasars dating back to the earliest epochs of the cosmos because they provide crucial insights into how the earliest galaxies and supermassive black holes originated.
Spotting them poses a major challenge because only a small number of galaxies had expanded sufficiently to house such phenomena during that early epoch, and the photons arriving at Earth today are exceptionally weak. Launched in 2023, Euclid is transforming that search by surveying enormous regions of the sky and detecting faint objects.
“These early quasars date back to the Universe’s infancy,” said Daming of the Euclid team. “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.”
The Euclid Wide Survey findings
Prior to this, scientists had only detected a tiny fraction of the quasars that existed during the earliest stages of the cosmos. Most known examples were exceptionally luminous objects that stood out because they were easier to detect, leaving a limited sample that made it difficult to understand the broader population.
Euclid is transforming this landscape by pinpointing both the most luminous quasars and much dimmer specimens that previous detection efforts struggled to uncover. Its discoveries are providing scientists with a far more representative view of the ancient quasar population.
“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. It’s a unique tool for quasar hunting,” Daming said.
Among the 31 newly identified quasars, 12 have a redshift of 7 or greater. The expansion of the cosmos stretches light—a phenomenon known as redshift—which allows researchers to calculate how distant an astronomical body is and how far back in cosmic time its radiation started its journey. A redshift of at least 7 places these quasars within the Universe’s first 770 million years.
Two record-breaking objects
Two objects stand out as particularly extraordinary among the findings. Featuring a redshift of 7.77, EUCL J172902.75+641018.1 stands as the most ancient, whereas EUCL J125308.55+705432.3 exhibits a redshift of 7.69. Situated just over 13 billion light-years from Earth, both objects were already radiating within the initial 670 million years of cosmic time. These discoveries establish new records for the earliest known quasars, surpassing a 2021 object with a redshift of 7.64.
“This finding more than doubles the number of quasars we know of that are so ancient,” said Antonio La Marca, an ESA Research Fellow in the Euclid team. While it took researchers over ten years to catalog roughly the first 10 quasars exhibiting redshifts of 7 or greater, Euclid exceeded that total in a mere twelve months.
“The Euclid team has taken a true ‘census’ of quasars at the dawn of the Universe for the first time,” Antonio told ScienceDaily. “It’s a big step towards understanding these fascinating objects on a more fundamental level.”
Researchers observe early supermassive black hole and star formation
Recent detailed examinations of the second oldest quasar found by Daming’s team were carried out by Silvia Belladitta and her associates. According to reports from the European Space Agency, their findings showed that the quasar resides inside a dusty, gas-rich galaxy experiencing an exceptionally high rate of new star formation.
This provides an important glimpse of the environment surrounding an early supermassive black hole and helps researchers understand how the first massive galaxies evolved alongside the black holes at their centers. These quasars belong to a transformative chapter in cosmic history known as the epoch of reionization, when the Universe emerged from a cold, dark state as increasingly energetic radiation heated the surrounding gas and ionized it.
“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,” said Valeria Pettorino, ESA Euclid Project Scientist.
Data from the Euclid Wide Survey—an ambitious initiative designed to ultimately map over one-third of the entire sky—was used to discover all 31 quasars.
