Korea-Japan Joint Observation Success of the Brightest Celestial Phenomenon in Space

Korea Astronomy and Space Science Institute Observes Birth Moment of Radio Lobes in Active Galactic Nucleus '3C84' with Japan, USA, and Italy

[Asia Economy Reporter Kim Bong-su] South Korea and Japan have collaborated to capture a special moment occurring in one of the brightest celestial objects in space, the Active Galactic Nuclei (AGN).

The Korea Astronomy and Space Science Institute announced on the 13th that an international joint research team from South Korea, Japan, the United States, and Italy, including Dr. Wajima Kiyoaki, observed the moment of birth of a radio lobe created by the powerful jet ejection from the active galactic nucleus ‘3C 84’.

A radio lobe refers to a large-scale luminous region formed when high-energy jets ejected from the supermassive black hole at the center of an active galactic nucleus violently collide with the surrounding high-density gas. It is usually a symmetrical structure located on both sides of the active galactic nucleus, with light at radio wavelengths forming a leaf-like shape, hence called a ‘radio lobe.’ Typically, its size is much larger than the galaxy itself.

Using the Korea-Japan joint space radio observation network (KVN and VERA Array, KaVA), which consists of seven radio telescopes jointly operated by the Korea VLBI Network (KVN) of the Korea Astronomy and Space Science Institute and the VERA Array of the National Astronomical Observatory of Japan, the team conducted long-term precise radio observations of the active galaxy 3C 84 over five years from 2015 to 2019.

The observations revealed that the hotspot at the end of the jet ejected from the supermassive black hole at the center of galaxy 3C 84 suddenly stopped moving for about one year from July 2016 to the end of 2017. From 2018, the hotspot and the surrounding radio lobe began moving again, but later the hotspot disappeared, the shape of the radio lobe became distorted, and its brightness decreased. Analysis of the observational data showed that this phenomenon is caused by the jet ejected from the supermassive black hole violently colliding with the surrounding high-density gas, significantly affecting the progression and growth process of the active galactic nucleus’s radio lobe.

The research team aimed to observe the movement of the radio lobe located only 4 light-years from the supermassive black hole at the center of galaxy 3C 84, using the 43 GHz frequency band of the Korea-Japan joint space radio observation network (KaVA) almost monthly from 2015 to 2019. They also utilized observation data from the Very Long Baseline Array (VLBA) of the U.S. National Radio Astronomy Observatory, which allows high-resolution radio observations, to obtain images with enhanced observational precision.

3C 84 is an active galaxy located at the center of the Perseus galaxy cluster, about 230 million light-years from Earth. In particular, the active galactic nucleus at the center of an active galaxy emits large amounts of energy across various wavelengths. It is known that most active galaxies harbor supermassive black holes at their centers, with masses ranging from millions to tens of billions of times that of the Sun. These supermassive black holes pull in surrounding matter with immense gravitational energy, and powerful jets eject matter at speeds close to the speed of light from their centers.

In 2005, jet ejection from the active galactic nucleus at the center of galaxy 3C 84 was first discovered. By precisely observing galaxy 3C 84, it is possible to watch the birth and growth process of the initial radio lobe from the supermassive black hole’s jet, making this achievement important evidence that can newly explain the evolution caused by the interaction between black hole jets and surrounding matter.

Dr. Wajima Kiyoaki of the Korea Astronomy and Space Science Institute, who participated in this study, said, “It was completely unexpected that gas dense enough to stop the powerful jet of the active galactic nucleus could exist so close to the black hole,” adding, “By closely observing the peculiar growth process of this celestial object, we expect to unravel the mysterious formation process of active galactic nuclei and jets.”

Kim Ki-tae, head of the Radio Astronomy Division, also said, “This research result proves the world-class performance of the Korea-Japan joint space radio observation network KaVA,” and added, “Based on these observation results, we plan to continuously reveal the evolutionary process of active galactic nuclei by additionally integrating radio telescopes from China and Italy to utilize a super-large simultaneous observation network with even higher resolution.”

This content was produced with the assistance of AI translation services.