An international team of astronomers has identified 31 new quasars dating back to when the universe was between 600 and 800 million years old, representing just 5% of its current age. The discovery, published July 6 in Astronomy & Astrophysics, includes the two most distant quasars ever observed, including the new record-holder, designated EUCL J172902.75+641018.1, which corresponds to a cosmic age of about 670 million years.
How does the Euclid Space Telescope find these objects?
The Euclid Space Telescope, launched in 2023, identifies these ancient beacons by scanning thousands of square degrees of the sky with high sensitivity in both visible and near-infrared light. According to Xiaohui Fan, a Regents Professor of Astronomy at the University of Arizona Steward Observatory, Euclid is capable of detecting quasars 10 to 100 times fainter than those identified in previous wide-field surveys.
Because these objects are so distant, their light is stretched into the near-infrared spectrum due to the expansion of the universe, a phenomenon known as “redshift.” Previously, ground-based observations struggled to detect these signals because Earth’s atmosphere glows brightly in the infrared, often drowning out faint light. Euclid bypasses this by operating from space.
Before this discovery, only nine quasars had been confirmed at distances greater than “redshift seven.” The new findings have increased that total to 23, significantly expanding the catalog of known early-universe objects.
Why are these quasars important for understanding the early universe?
Quasars act as cosmic lighthouses during the “epoch of reionization,” a period when the first stars and galaxies ionized the neutral hydrogen fog that permeated the early universe. By studying these energetic objects, researchers hope to understand how the cosmos transitioned from darkness to light.
However, the existence of these supermassive black holes—which possess the mass of billions of suns—presents a scientific puzzle. As noted by doctoral student and first author Daming Yang of Leiden Observatory, it remains unclear how such massive structures could form within only a few hundred million years following the Big Bang. Finding more of these objects is considered the only way forward to answering these questions.
What is the difference between current and previous quasar surveys?
Previous surveys were limited by the sensitivity of ground-based telescopes, which generally favored the most luminous, massive quasars. The current data from Euclid allows astronomers to study a more diverse population of black holes.
| Feature | Previous Surveys | Euclid Survey |
|---|---|---|
| Sensitivity | High-luminosity only | Detects 10–100x fainter objects |
| Volume | Limited total count | Hundreds expected over 6 years |
| Location | Ground-based | Space-based (Near-infrared) |
What happens next in this research?
The current discovery is based on only one year and a half of Euclid data. The full six-year survey is projected to uncover hundreds more high-redshift quasars, including the first z > 8 quasars.
Following the initial data, the next major release is scheduled for late 2026. This dataset will provide the largest map of the universe ever produced from space, which astronomers expect will also drive breakthroughs in understanding dark matter and dark energy by 2027.
While Euclid provides the wide-field survey capability, researchers must still use ground-based observatories, such as the Large Binocular Telescope (LBT) and the Magellan telescopes, to obtain the high-resolution spectroscopic data required for detailed analysis.
Frequently Asked Questions
What is a quasar?
A quasar is an extremely bright and energetic object powered by a supermassive black hole that is actively consuming matter at the center of a galaxy.
Why is it difficult to see these objects?
Because they are billions of light-years away, their light is “redshifted” into the near-infrared spectrum. Earth’s atmosphere naturally glows in these wavelengths, making it difficult for ground-based telescopes to see them clearly.
How old are the quasars mentioned in this report?
These objects date back to a time when the universe was between 600 and 800 million years old, or roughly 5% of its current age.
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