Recently, Xin Zhang's team from NEU has made important progress in the study of gravitational wave cosmology, and the relevant achievements were published in the comprehensive physics journal, Science China Physics, Mechanics & Astronomy’s English Edition (District 1 of the Chinese Academy of Sciences), which was selected as the cover paper of the third issue of the journal in 2024. Jiyu Song, a doctoral student from NEU, is the first author of the paper, and Prof. Xin Zhang is the corresponding author.
The Hubble constant crisis has become a major puzzle in cosmology over the past decade. The research findings indicate that the Chinese Survey Space Telescope (CSST) of Chinese Space Station Program shows great potential in solving this problem.
CSST is a large space astronomical telescope planned and constructed by the China Manned Space Engineering Program, with an aperture of 2 m, excellent performance of both large field of view and high image quality, and the capability of on-orbit maintenance and upgrading. With large-scale space survey as its main task, CSST is the most important core scientific facility of the Chinese Space Station Program, and is also China's new-generation flagship space astronomical telescope with the largest scale and the most advanced indicators to date. The CSST is expected to be launched around 2027, and its scientific objectives involve cutting-edge hotspot directions and major scientific issues in the field of astronomy, such as dark matter, dark energy, cosmology, the origin and evolution of galaxies, stars, solar system and exoplanets.
Most gravitational wave events originate from binary black hole mergers, and these events are usually not accompanied by electromagnetic wave signals. Due to the lack of an electromagnetic counterpart, it is difficult to directly measure the red shifts of these events, thus limiting their application in exploring the evolution of the universe. However, the redshifts of these gravitational wave events can be indirectly determined based on galaxy catalogs obtained from large-scale space surveys of galaxies. This method is known as the "gravitational wave dark siren".
At present, GLADE + galaxy catalog is used to support the study of “gravitational wave dark siren”, but its integrity is not enough to meet the needs of the third-generation ground gravitational wave detector in the future. In contrast, CSST will provide the more complete and high-quality galaxy catalogs, which will play a vital role in the future study of “gravitational wave dark siren”.
This research shows that combining CSST’s galaxy catalog with about 300 dark siren events observed by the third-generation ground gravitational wave detector, the measurement accuracy of Hubble constant can be improved to below 1%. This accuracy far exceeds the actual observation results of “gravitational wave dark siren” at present. The combination of CSST’s space survey and gravitational wave research indicates an important step in solving the Hubble constant crisis.
This research is supported by National Key Research and Development Program “China Square Kilometer Array (SKA) Special Project”, National Natural Science Foundation of China, China Manned Space Project and 111 Project of Intelligence Introduction Program.
