Space gravitational wave antenna DECIGO and B-DECIGO

DECi-hertz Interferometer Gravitational-wave Observatory (DECIGO) is a future Japanese space gravitational-wave antenna. There are many science targets that DECIGO aims at, including the detection of primordial gravitational waves, direct measurement of the acceleration of the Universe, the revelation of the formation of massive black holes, and many others. DECIGO consists of four clusters of spacecraft, and each cluster consists of three spacecraft with three Fabry-Perot Michelson interferometers. As a pathfinder mission of DECIGO, we plan to launch B-DECIGO to demonstrate technologies necessary for DECIGO as well as to lead to fruitful multimessenger astronomy. B-DECIGO is a small-scale version of DECIGO with a sensitivity good enough to provide frequent detection of gravitational waves. In this talk, the aimed science, the mechanical and optical design, and the current status of DECIGO and B-DECIGO will be explained in detail.