In addition to the high-energy frontier, there exists a frontier that is characterized by ultra-light and ultra-weak phenomena. Detection of ultralight wave-like dark matter is an important aspect in addition to gravitational wave detection. When particle mass is extremely light, its de Broglie wavelength reaches the galactic scale. This makes detection possible through gravitational wave detection and radio astronomy observation methods. Phase transitions in the early universe may have left various topological defects. The evolution of first-order phase transitions or topological defects can produce a stochastic gravitational wave background. Recent advances in pulsar timing array astronomy (e.g., future square kilometer array SKA), Gaia astrometry observation for star positions, and detection by the Event Horizon Telescope (EHT) have led to the detection of gravitational wave phenomena and ultralight dark matter. With the further development of related experiments, better detection accuracy of ultra-light dark matter and gravitational wave related physics can be achieved, which will allow us to gain breakthrough understanding of the possible fundamental physical laws behind them.
