Chinese Sky Survey Pinpoints Interstellar Clouds in Cosmic Ray Origins

Data from China's 'Milky Way Imaging Scroll' sky survey has confirmed that interstellar molecular clouds serve as key carriers in the birth of ultra-high-energy cosmic rays, according to state media reports. Conducted by researchers using the 13.7-meter radio telescope at the Delingha station in Qinghai Province under the Purple Mountain Observatory, the ongoing observational project provides critical observational evidence toward resolving a long-standing puzzle in high-energy astrophysics regarding the origin and acceleration mechanisms of cosmic rays.

Understanding the origin of ultra-high-energy cosmic rays is one of the central problems in modern astrophysics. By linking cosmic ray production directly to interstellar molecular clouds, the survey offers crucial empirical constraints that bridge radio astronomy and high-energy astrophysics. The findings demonstrate how systematic, wide-field galactic surveys can unlock fundamental physics mechanisms within the Milky Way.

China's "Milky Way Imaging Scroll" sky survey has confirmed that interstellar molecular clouds play a crucial carrier role in the generation of ultra-high-energy cosmic rays, according to a report by China News Service. The finding offers pivotal observational evidence toward addressing a foundational puzzle in high-energy astrophysics regarding where and how these extraordinarily energetic particles originate and interact within the galaxy. The ongoing astronomical survey relies on observational data gathered by the Purple Mountain Observatory under the Chinese Academy of Sciences. Utilizing the observatory's 13.7-meter millimeter-wave radio telescope located at the Delingha station in Qinghai Province, researchers have been systematically mapping the molecular gas distribution along the Milky Way's galactic plane with high spatial resolution and sensitivity. Cosmic rays—high-energy protons and atomic nuclei traveling through space near the speed of light—have long challenged astrophysicists because interstellar magnetic fields deflect their trajectories, obscuring their direct points of origin. Interstellar molecular clouds serve as dense target environments where energetic particles accelerated by cosmic accelerators interact with ambient gas, producing detectable secondary radiation such as high-energy gamma rays. By mapping molecular cloud structures in detail, the survey enables scientists to trace these interaction sites and clarify particle acceleration dynamics. The "Milky Way Imaging Scroll" represents one of China's primary systematic projects in radio astronomy. Precise wide-field surveys of molecular spectral lines, particularly carbon monoxide, provide an essential baseline for identifying candidate cosmic ray acceleration sites, such as supernova remnants, stellar wind bubbles, and massive star-forming regions embedded within interstellar gas clouds. Looking ahead, the comprehensive dataset compiled by the survey is expected to drive further interdisciplinary investigations connecting radio astronomy, high-energy particle physics, and computational data science. As sky survey datasets grow in both scale and complexity, the integration of automated data processing and machine learning tools will be critical for uncovering subtle astrophysical correlations. The findings from the Purple Mountain Observatory establish a valuable foundation for future multi-wavelength and multi-messenger research into galactic particle acceleration mechanisms.