和 英 Tsukuba Uchu Forum
148th Uchu Forum
Nancy Grace Roman Space Telecope: Challenge to Open New Vision of the Universe
Toru Yamada
Institute of Space and Astronautical Science, JAXA
Abstract
The launch of the Nancy Grace Roman (*) Space Telescope (hereafter referred to as "Roman") is now just about two years away. Roman is NASA's next major astrophysics mission following the James Webb Space Telescope. It features a 2.4-meter aperture optical telescope and a wide-field near-infrared imaging and spectroscopic instrument with 288-megapixel, offering a field of view approximately 200 times larger than the Hubble Space Telescope. Roman aims to conduct precise measurements of the accelerating expansion of the universe and to study the nature of dark energy, to perform comprehensive and detailed measurements of the history of cosmic structure formation, to survey the distribution of exoplanets, and to address various astronomical questions through wide-field near-infrared observations. Additionally, Roman will be equipped with Coronagraph Instrument for direct imaging of exoplanets, alongside its main instrument, the Wide Field Instrument. This coronagraph, as a technology demonstration, is considered an essential and important step toward future direct observations of Earth-like planets orbiting in the habitable zones of Sun-like stars, such as those that could be made by missions like the Habitable Worlds Observatory. Currently, Roman is in its final stages of development, targeting a launch in October 2026. Since the early phase, Japanese researchers have participated in the Roman telescope project through JAXA (Japan Aerospace Exploration Agency), contributing to the scientific planning, instrument development, and ground station operations, including the reception of large-scale observation data via JAXA ground stations. Additionally, they are contributing through coordinated synergistic observations using ground-based telescopes with unique and complementary capabilities, such as Subaru Telescope (NAOJ) and PRIME telescope (Osaka University). In this lecture, I will introduce the expected data that the Nancy Grace Roman Space Telescope aims to acquire, and discuss the new perspectives on the universe that Roman is expected to open up in the fields of cosmology, galaxy formation and evolution, and exoplanets. I will also touch on the current status of the Roman project, as well as Japan's contributions and scientific collaborations. The data obtained in the survey observations, which will occupy 75% of Roman's observation time, will be made publicly available to researchers worldwide soon after the observations are completed, while the remaining 25% of the time will be dedicated to general observation proposals for various guest research projects. I hope many researchers will make full use of the Roman data. The speaker has previously conducted research on galaxy formation and evolution through wide-field observations with the Subaru Telescope. In order to further extend such observations of emission-line galaxies and star-forming galaxies to higher redshifts, or to obtain near-infrared data that complement wide-field visible light observations, such as stellar-mass-based galaxy observations or red galaxies affected by absorption, the Roman Space Telescope represents a "natural progression" from the wide-field observations made by Subaru. From this perspective, I would also like to discuss what I expect for Roman, particularly with a focus on the large-scale structiore of high-redshift star-forming galaxies and 'galaxy formation regions'. (*) Footnote: The name Nancy Grace Roman refers to one of NASA's pioneering astronomers and the "mother" of the Hubble Space Telescope.