[Reading Science] EHT Captures World's First Magnetic Field Changes in a Supermassive Black Hole

Key Contribution by Korean Researchers in Multi-Year Analysis of 2017, 2018, and 2021 Observation Data

The Event Horizon Telescope (EHT), which is operated to capture images of black holes, has re-observed the shadow and ring of light structure of the black hole at the center of the Messier 87 (M87) galaxy.

The EHT is an international collaborative project that connects radio telescopes scattered across the globe to create a virtual telescope the size of Earth in order to capture images of black holes. M87 is a massive elliptical galaxy located near the center of the Virgo Cluster, about 55 million light-years from Earth. At its center lies a supermassive black hole with a mass approximately 6.5 billion times that of the Sun.

The M87 black hole images observed by the Event Horizon Telescope (EHT) show results from 2017, 2018, and 2021 from left to right. The thin lines above the ring represent the strength and direction of the magnetic field. While the size of the black hole's shadow and the ring remain almost constant, the position of the brightest part and the shape of the magnetic field change year by year. Provided by the Space Agency.

The Space Aeronautics Agency and the Korea Astronomy and Space Science Institute announced on the 16th that, through the EHT international collaborative research project involving Korean researchers, they have once again observed the shadow and ring of light structure of the supermassive black hole at the center of the M87 galaxy.

The newly observed image was captured in 2021, showing the black hole three years after the 2017 and 2018 data, which revealed the first-ever photograph of a black hole to humanity.

Korean researchers, centered around the Korea Astronomy and Space Science Institute, Kyung Hee University, and Ulsan National Institute of Science and Technology (UNIST), conducted a comparative analysis of the 2017, 2018, and 2021 data, focusing on temporal changes in the M87 black hole.

The Korean research team made a key contribution to the EHT by utilizing software they developed themselves to analyze changes in the magnetic field structure around the black hole. The EHT confirmed that while the size of the black hole's shadow (the central dark region) and the surrounding ring of light remained consistent, the direction of the ring of light-specifically, the spiral pattern of the magnetic field around the black hole-changed from year to year.

Notably, in 2021, the direction of rotation of the magnetic field was the opposite of that observed in 2017. This change in the magnetic field is interpreted as the result of a combination of the internal magnetic field structure of the light-emitting region and the influence of surrounding matter. This suggests that the material near the black hole is moving in a highly dynamic manner and indicates that further research is needed to supplement existing theories.

Since 2017, the EHT has continued to announce new research findings by observing M87 in 2018, 2021, 2022, 2024, and 2025.

In 2026, the EHT plans to be the first in the world to intensively observe the black hole over three months, capturing one image every two weeks-compared to the previous rate of one image per year-in order to create a video showing short-term changes in the black hole. The Korean VLBI Network (KVN), operated by the Korea Astronomy and Space Science Institute, is scheduled to participate directly in these future projects.

Son Bongwon, principal researcher at the Korea Astronomy and Space Science Institute, said, "Major research, including these latest results, is being led by young Korean researchers. Korea is now a core nation in EHT black hole research, as we are also spearheading the development of next-generation key technologies."

Kang Kyungin, director of the Space Science Exploration Division at the Space Aeronautics Agency, stated, "This achievement is an important step forward in understanding the extreme environments of the universe, such as black holes. We will continue to actively support world-class space observation research to broaden humanity's horizons of knowledge and ensure that Korea leads in space science."