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Astrophysics

Euclid: Discovery of 31 new quasars at 6.6 < z < 7.8

D. Yang, J. F. Hennawi, F. Guarneri, J. Wolf, S. Belladitta, J.-T. Schindler

Featured July 8, 2026

Original Paper

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Simply

Using *Euclid* space telescope data, scientists found 31 new super-distant quasars, including the farthest ever seen, by using smart computer programs to pick out faint, glowing objects from billions of stars.

In depth
This study reports the discovery of 31 new high-redshift quasars, including the most distant known quasar at , using initial data from the Euclid Wide Survey. The authors employed a sophisticated multi-algorithm photometric selection pipeline combining machine learning and probabilistic techniques to identify faint, distant quasar candidates, followed by spectroscopic confirmation with large ground-based telescopes. This significantly expands the sample of known quasars at , probing the faint end of the quasar luminosity function in the early Universe.

Key Takeaways

  • 1
    The paper reports the discovery of 31 new high-redshift quasars () from the initial 1.5 years of the Euclid Wide Survey, more than doubling the number of known quasars at .
  • 2
    A multi-algorithm photometric selection pipeline, integrating Extreme Deconvolution, XGBoost, template-based SED fitting, and Bayesian model comparison, was crucial for efficiently identifying these rare, faint candidates from vast *Euclid* imaging data.
  • 3
    The newly discovered quasars extend studies to the faint end of the quasar luminosity function at , providing unique insights into supermassive black hole growth and the intergalactic medium during the epoch of reionisation.

Conceptual Flow

HIGH LEVEL
1
Methodology: Finding Distant Quasars

The scientists used a space telescope to take many pictures, then used smart computer programs to find tiny, faint, distant objects that might be special, and finally checked them with big ground telescopes.

Space Telescope
Raw Sky Pictures
Process & Analyze
Computer Picks
Ground Telescope Check
2
Results: New View of Early Universe

They found many more super-distant quasars than before, including the farthest one ever, showing that the early universe had more bright objects than we thought, helping us understand how everything began.

Few Known Distant Objects
Limited Brightness Range
New Discoveries
Many More Distant Objects
Wider Brightness Range