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6h ago

Euclid Doubles Known Earliest Quasars and Sets New Redshift Records

Space-based near-infrared imaging with machine-learning selection produced a confirmed sample that has prompted JWST and ALMA programs to measure black-hole masses and host galaxies.

Artist's concept of a quasar. Quasars are some of the most luminous events in the universe. They are the result of black holes in the early universe undergoing feeding frenzies. Of the 31 newly discovered quasars by the Euclid space telescope, 2 are the most ancient quasars yet found. Image via ESA.
This collage shows 15 of the 31 newly discovered quasars by ESA’s Euclid space telescope. EUCL J172902.75+641018.1 and EUCL J125308.55+705432.3 are visible on the first row, the first and second from the left, respectively. Image credit: ESA / Euclid / Euclid Consortium / NASA / Euclid Science Ground Segment / Antoine Basset, CNES.

Overview

  • The Euclid Consortium reports 31 quasars from the epoch when the universe was about 670–800 million years old, more than doubling the known population at redshift z ≳ 7.
  • Two objects in the sample, EUCL J172902.75+641018.1 and EUCL J125308.55+705432.3, have redshifts of 7.77 and 7.69 respectively, making them the most distant quasars yet reported.
  • Euclid's space-based near-infrared survey reduced atmospheric foregrounds and, together with machine-learning classifiers, separated rare high-redshift quasars from millions of lookalike sources.
  • Ground telescopes including Keck have spectroscopically confirmed roughly two thirds of the candidates, and the sample sharpens the puzzle of how billion-solar-mass black holes grew so rapidly in the first billion years.
  • The team has secured follow-up with the James Webb Space Telescope and plans ALMA observations to measure black-hole masses, host dust and gas, and the quasars’ role in reionization while Euclid’s ongoing wide survey is expected to find many more such objects.