Scientific objectives of the Xue-shan-mu-chang 15-meter SubMillimeter Telescope

Submillimeter astronomy is poised to revolutionize our understanding of the Universe byrevealing cosmic phenomena hidden from optical and near-infrared observations, particularly thoseassociated with interstellar dust, molecular gas, and star formation. The Xue-shan-mu-chang 15-meterSubMillimeter Telescope (XSMT-15m), to be constructed at a premier high-altitude site (4813 m) in Qinghai,China, marks a major milestone for Chinese astronomy, establishing the Chinese mainland first independentlydeveloped, world-class submillimeter facility. Equipped with state-of-the-art instruments, XSMT-15m willaddress a diverse range of frontier scientific questions spanning extragalactic astronomy, Galactic structure,time-domain astrophysics, and astrochemistry. In synergy with current and forthcoming observatories,XSMT-15m will illuminate the formation and evolution of galaxies, unravel the physical and chemicalprocesses shaping the interstellar medium, and explore transient phenomena in the submillimeter regime.These capabilities will advance our understanding across extragalactic astronomy, Galactic ecology, astrochemistry,and time-domain astrophysics, inaugurating a new era for submillimeter research in China and the northern hemisphere.