Subaru Telescope: 20 Years of Observing the Heavens

The Subaru Telescope’s combination of light-collecting power and wide field of view allow it to conduct deep and wide surveys of the Universe. Cosmological observation, which explores the history of the entire Universe, is one field where the Subaru Telescope demonstrates its unique abilities. Careful examination of the detailed spatial distributions of galaxies is essential to understand structure formation in the Universe. The Fiber Multi-Object Spectrograph (FMOS) mounted at the prime focus conducted such a survey and successfully created a distribution map of galaxies 13-billion light-years away. Data from the survey provided valuable information on the growth rate of the large-scale structure of the distant Universe.

The wide field-of-view and superior imaging performance of HSC enable us to investigate “images” of a number of galaxies. While any gravity source between the galaxies and us distorts the images of the galaxies, these distortions conversely reveal the spatial distributions of the invisible gravity source known as dark matter. Through this approach, the Subaru Telescope analyzed images of 20 million galaxies and created a 3D map of the dark matter distribution in the Universe. This is the largest and most detailed dark matter map ever created. The detailed analysis also suggested that the rate of mass accumulation is slightly slower than theoretical estimates.