Oldest Galaxy Protocluster forms “Queen’s Court”

Using the Subaru, Keck, and Gemini Telescopes, an international team of astronomers has discovered a collection of 12 galaxies in the constellation Cetus which existed about 13.0 billion years ago. This is the earliest protocluster ever found. One of the 12 galaxies is a giant object, known as Himiko, which was discovered a decade ago by the Subaru Telescope and named for a legendary queen in ancient Japan. This discovery suggests that large structures such as protoclusters already existed when the Universe was only about 800 million years old, 6 percent of its present age.

This research will be published on September 30, 2019 in The Astrophysical Journal as Yuichi Harikane, et al. “SILVERRUSH. VIII. Spectroscopic Identifications of Early Large Scale Structures with Protoclusters Over 200 Mpc at z~6-7: Strong Associations of Dusty Star-Forming Galaxies”. This work was supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) and the Japan Society for the Promotion of Science.