A team of astronomers led by Joseph Hennawi of the Max Planck Institute for Astronomy, using the W.M.  Keck observatory in Hawaii, have discovered the first quadruple quasar: four quasars with approximately the same redshift of about z ~ 2 and located on the sky in close proximity.  The online article¹ from Max Planck Institute is titled “Quasar quartet puzzles scientists” with the subtitle “Astronomers must rethink models about the development of large-scale cosmic structures.” This is a discovery of the first known group of four quasars with the same redshift found in the same location on the sky. A research paper has been accepted for publication in the journal Science and a preprint is now available.²

The quartet resides in one of the most massive structures ever discovered in the distant universe, and is surrounded by a giant nebula of cool dense gas. Either the discovery is a one-in-ten-million coincidence, or cosmologists need to rethink their models of quasar evolution and the formation of the most massive cosmic structures.¹

Caption from original article: Rare find: This image depicts the region in space with the quadruple quasars. The four quasars are indicated by arrows. The quasars are embedded in a giant nebula of cool dense gas visible in the image as a blue haze. The nebula has an extent of one million light-years across, and these objects are so distant that their light has taken nearly 10 billion years to reach telescopes on Earth. This false color image is based on observations with the 10-m-Keck-telescope on the summit of Mauna Kea in Hawaii. Credit: Arrigoni-Battaia & Hennawi / MPIA  (Ref. 1)

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