An international team of astronomers discovered 31 quasars using the European Space Agency's Euclid telescope, including the two oldest observed to date. The light from these quasars originates from when the universe was approximately 670 million years old, representing five percent of its current age of 13.8 billion years. This discovery surpasses the previous record for the oldest quasar, announced in 2021, by approximately 20 million years.

The two most ancient quasars are designated EUCL J172902.75+641018.1 and EUCL J125308.55+705432.3, with redshifts of 7.77 and 7.69 respectively. Located just over 13 billion light-years from Earth, they are among 12 new quasars identified at a redshift of 7 or above, corresponding to the first 770 million years of the universe. These objects date back to the epoch of reionization, the period when the first stars and galaxies began to form. Quasars are powered by supermassive black holes consuming surrounding matter and can shine trillions of times brighter than the sun.

Daming Yang, a PhD student at Leiden University in the Netherlands and lead author of the study published in Astronomy & Astrophysics, said, "Euclid is a true game-changer." Yang added, "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." He noted, "It's a unique tool for quasar hunting." Yang explained, "We can use quasars as a lighthouse to study the gas between us and them, so that we can trace how the universe was reionized through this cosmic history." He also stated, "These early quasars date back to the Universe's infancy. 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."

Co-author Joseph Hennawi said, "Every step further back in time makes the puzzle more perplexing." Hennawi added, "These monsters -- weighing billions of times the mass of our sun -- somehow already existed when the universe was in its infancy. We don't yet have a good understanding of how they grew so massive, so fast." He commented that the team hopes to "stitch together a quasar chronicle of the first billion years."

Antonio La Marca, an ESA Research Fellow on the Euclid team, said, "This finding more than doubles the number of quasars we know of that are so ancient." La Marca added that the team has taken a "true 'census' of quasars at the dawn of the Universe for the first time."

The Euclid telescope launched on July 1, 2023, from Cape Canaveral atop a SpaceX Falcon 9 rocket. The $1.5 billion mission is scheduled to last six years and aims to chart one-third of the sky. The telescope is positioned at a stable point approximately 1.5 million kilometers from Earth.

Why It Matters

The discovery provides data from the early universe, specifically the epoch of reionization. Studying these quasars can help astronomers understand how supermassive black holes formed and grew rapidly during this time. The Euclid telescope's ability to identify fainter, more distant quasars expands observations into the universe's early stages, more than doubling the known number of such ancient objects.