Discovering the Most Ancient Quasars in the Universe

LSA researchers were part of an international team that used the European Space Agency’s Euclid space telescope to discover 31 of the most ancient quasars ever observed. They are so old, in fact, that they date back to the universe’s so-called reionization era, when stars, galaxies and supermassive black holes were first forming.

“This is truly exciting,” says Jinyi Yang, co-author of the new study published in the journal Astronomy & Astrophysics and assistant professor in the Department of Astronomy. “These luminous quasars, shining from deep within the reionization era, the last major transition in our universe’s history, offer invaluable insights into how the cosmos emerged from darkness and how the earliest supermassive black holes formed.”

Quasars are among the brightest, most energetic objects in the universe and are powered by supermassive black holes devouring matter at the center of galaxies. They are short-lived compared to a galaxy’s lifetime, but in that relatively brief moment, quasars can outshine the rest of their host galaxies by hundreds to thousands of times.

By finding the most distant quasars, astronomers can learn more about the early universe. But ancient quasars are rare because few galaxies had enough time to grow large enough to host one. These quasars are also hard to find because their primordial light is both faint and easy to confuse with stars.

But Euclid, which began its cosmological survey in February 2024, is ushering in a new era in that search, said study co-author Feige Wang, U-M assistant research scientist in astronomy.

“The Euclid mission is completely changing the game,” Wang says. “Of those 31 quasars, 12 are above redshift 7, more than doubling all the known quasars that are beyond redshift 7.”

Redshift is a measure of how much the wavelength of light from an astronomical object has been stretched due to the expansion of the universe. Light that travels longer to reach us—that is, light from distant sources that was emitted long ago—will have higher redshifts. In this sense, observing objects with high redshifts allows astronomers to look back in time and study the universe when it was younger, Wang said.

Previously, the record for the most distant quasar was held by one discovered in 2021 by Wang and Yang with a redshift of 7.64. The new study includes two quasars that break that record: one with a redshift of 7.69 and another with a redshift of 7.77. That means both emerged within 670 million years of the Big Bang and their light took more than 13 billion years to reach us.

Read more at Michigan News. 

Image credit: ESA. This artist’s impression shows a quasar: a brief period of life for a big, bright galaxy during which large quantities of material spiral into its central supermassive black hole, releasing energetic light as it does so. Researchers using the European Space Agency’s Euclid space telescope have discovered 31 of the universe’s most ancient quasars.