Subaru Telescope: 20 Years of Observing the Heavens

One of the primary scientific objectives of the Subaru Telescope is to explore the distant Universe and understand the evolution of galaxies. The Prime Focus Camera, Suprime-Cam, started its operation right after the Subaru Telescope’s first light. Suprime-Cam had an exceedingly wide field-of-view and high sensitivity even among large telescopes of the time, and had a great impact on surveys of the distant Universe. Based on observations of Lyman-alpha radiation from distant galaxies, the Subaru Telescope broke the record for “the most distant galaxy” multiple times and eventually discovered a galaxy at a redshift of 7 (located 12.88 billion light-years away). At that point, nine out of the ten most distant galaxies had been discovered by the Subaru Telescope.

Early on, the Subaru Telescope launched something called “Observatory Projects” and conducted large survey programs over dozens of nights. Data obtained from one of the projects “XMM–Newton Deep Field” revealed an extremely large and bright ionized gas cloud located 12.9 billion light-years away. This object, dubbed “Himiko,” is thought to be a giant galaxy with intense star formation in the early phase of galaxy formation and likely holds the key to solve the mysteries of galaxy formation

Data obtained from another Observatory Project called “Subaru Deep Field” discovered the most distant galaxy cluster (located 12.7 billion light-years away). This finding showed that galaxy clusters consisting of hundreds of galaxies already existed when the Universe was only a billion years old.

Furthermore, a large-scale survey using HSC, the successor to Suprime-Cam, discovered as many as two hundred protoclusters of galaxies 12 billion light-years away.