Hanyang University announced on November 24 that the joint research team led by Professors Cheon Byung-gu and Kim Hang-bae, from Hanyang University's Department of Physics discovered a cosmic ray with an energy of 244 EeV based on 15 years of observational data. The research team, along with Professor Ryu Dong-su from UNIST and Professor Park Il-Hung from Sungkyunkwan University, have participated in an international collaborative research involving South Korea, the United States, Japan, and Russia. If these particles were to accumulate with the mass of 1g, they could generate astronomical energy equivalent to approximately 100 billion nuclear bombs with a power of 20 kilotons of TNT.

Particles with high energy continuously travel through space and fall to Earth. These particles, known as “cosmic rays,” have been known since their discovery in 1912, yet their origin, formation, and migration mechanisms remain unknown even after more than 100 years.

The Telescope Array (TA) international research team started experimental observations on the origin of cosmic rays in 2008. They installed over 500 surface detectors with a 1.2 km spacing and three large telescope array stations in a desert in Utah, the size of Seoul city, Korea. In May 2021, they detected an “Extremely energetic cosmic ray” with the highest observed energy level in their history.

The origin of extremely energetic cosmic rays is speculated to be associated with the largest explosions in the universe, such as gamma-ray bursts, relativistic jets from massive black holes at the centers of active galactic nuclei, or neutron stars with the greatest energy.

Surprisingly, the discovered cosmic rays were confirmed to come from empty space without a specific celestial body as their origin. This finding presents a mysterious event where cosmic particles with tremendous energy originate from “empty space.” The research team's observations suggest possibilities beyond astrophysical phenomena and standard models, hinting at a new physical origin.

Unlike regular cosmic rays, extremely energetic cosmic rays are easily traceable due to their less easily curved paths in the cosmic magnetic field. Therefore, the discovery opens up possibilities for the field of “Next-generation Astrophysics.” To further explore this, the TA international research team is conducting an upgrade experiment called “TA×4,” with joint participation from South Korea, the United States, and Japan, aiming to increase the frequency of particle detection fourfold.

Professor Cheon Byung-gu expressed expectations for this achievement, stating, "Through the observation of extremely energetic cosmic rays, it is anticipated that we will be able to create a cosmic map of celestial sources." He added, "This research will deepen our understanding of the universe."

Dr. Kim Ji-hyun, who earned a Ph.D. in physics from Hanyang University, played a significant role in the data analysis for this paper while working as a researcher at the University of Utah.

This research, bearing fruit after 15-years of observation, was conducted with support from the National Research Foundation of Korea’s Global Research Development Center (GRDC) and Mid-career Researcher Support Program. The paper was published online in "Science" on November 24 (Korean time).