The boy who grabbed the M87 sign on the mountain… 20 years later he became the hero of the soap opera “The Second Black Hole”

The EHT International Joint Research Team has detected, for the first time, a supermassive black hole located in the center of the Milky Way, “Sagittarius A”. [사진=천문연]
An image of Sagittarius A black hole observed this time.  The black part in the center is the black hole (the event horizon) and the shadow that contains the black hole, and the bright part of the ring bends the light by the black hole's gravity. [사진=천문연 제공]
An image of Sagittarius A black hole observed this time. The black part in the center is the black hole (the event horizon) and the shadow that contains the black hole, and the bright part of the ring bends the light by the black hole’s gravity. [사진=천문연 제공]

An international research team involved with the Event Horizon Telescope (EHT) captured a supermassive black hole at the center of our galaxy for the first time and released the image at 10:07 p.m. on the 12th. Sagittarius A. black hole discovered by mankind after M87, which was first discovered in 2019, as the Korea Institute of Astronomy and Space Science called it.

Sagittarius: The black hole is located in the center of the Milky Way, about 27,000 light-years from Earth, and has a mass about 4 million times the mass of the Sun. Compared to the M87 black hole, its distance from the solar system is close to 1/2000, making it a prime target for black hole research. However, since its mass is 1,500 times less than that of M87, the gas flow around the black hole changes rapidly and the image suffers from strong scattering, which makes observation difficult compared to M87.

The joint research team has successfully observed black holes using EHT. The EHT is an attempt to capture images of a black hole by connecting radio telescopes around the world to create a hypothetical Earth-sized telescope. 80 institutions around the world, 300 researchers and 8 radio telescopes have been mobilized for 5 years.

Through Korea’s Third Space Radio Observation Network (KVN) (Yonsei University in Seoul, Ulsan University and Tamna Radio Observatory in Seogwipo, Jeju), the Astronomical Research Institute has confirmed that the structure of the Sagittarius A black hole is close to the ‘circle’. With an international research team. This means that the correlation disk created when the surrounding gases are rotated and pulled by the black hole’s gravity has a circular shape, indicating that the black hole is facing Earth.

“The black hole and the M87 black hole have very similar shapes, according to Einstein’s theory of general relativity,” said Sarah Markov, co-chair of the EHT Science Council.

Keiichi Asada, Ph.D., an astrophysical researcher at the Central Academy of Sciences in Taiwan, said: “With this study, we compare and analyze images of the largest supermassive black hole, the M87 black hole, and the largest small arc black hole, see how gravity works in very different situations, more and more We can test it in more detail.

“A black hole is the closest black hole among black holes that humans directly observe with collective intelligence,” said Bong-Won Sun, Ph.D., of the Radio Astronomy Headquarters, who participated in the study. ‘study. We are preparing to participate directly in the event.

◆ The boy who picked up the M87 signal in the mountains… for everyone

The study was co-authored by Bong-Won-sun, Ph.D., Radio Astronomy Headquarters.  He specialized in radio astronomy and worked as a postdoctoral researcher at the Max Planck Institute for Radio Astronomy in Germany.  At the time, I was involved in the study of capturing signals from black holes near the event horizon. [사진=이유진 기자]
The study was co-authored by Bong-Won-sun, Ph.D., Radio Astronomy Headquarters. He specialized in radio astronomy and worked as a postdoctoral researcher at the Max Planck Institute for Radio Astronomy in Germany. At the time, I was involved in the study of capturing signals from black holes near the event horizon. [사진=이유진 기자]

The doctor. Sun was part of this research team when humans first picked up the signal from a black hole. After obtaining his master’s degree in radio astronomy at Yonsei University, he joined the doctoral program at the University of Bonn, Germany, and in 2002 he was a postdoctoral researcher at the Max Planck Institute for Radio Astronomy. For reference, Bonn was the center of black hole research at the time.

According to him, there was a boom in black hole research at the time of the lab. In addition to conventional observations of jet emissions from active galaxies, attempts have been made to capture signals from black holes near the event horizon using high-resolution telescopes. Luckily, he joined the research team and took on the responsibility of observing the event horizon. The signal successfully captured at this point is the starting point of the M87 black hole, which was captured by mankind for the first time.

☞ Event horizon: a large boundary region that connects the interior and exterior of a black hole. When matter crosses the event horizon and is sucked into a black hole, some is released as energy; So if you are using high resolution monitoring equipment, you can see the edge of the event horizon.

Agree with the doctor. Sound, very long video interferometry (VLBI) observations were recorded around this time. Collecting signals from Dark Orbs requires very precise timing, which Taperon doesn’t do well. A hard drive is required to monitor the level of the event horizon. At this time, a radio interferometer hard disk was developed, and the research team confirmed the possibility of using the first prototype. The result was a huge success, as he managed to pick up the signal from a black hole near the event horizon.

Very Long Baseline Interferometry (VLBI): several radio telescopes located hundreds or even thousands of kilometers apart simultaneously observe the same celestial body and implement a huge virtual telescope with an aperture corresponding to the distance between the radio telescopes for more than precision (lower resolution). A technique that increases the ability to distinguish between two things.

Dr. Son said, “At the time, I was the youngest member of the team with a post-doc, so I used to climb the mountain with the first prototype and watch it for 12 time. Not everyone was sure he would, but the sighting went well. It was a watershed moment in the study of black holes.

◆ Korea’s late performance? “Result of perseverance”

Korea Satellite Radio Monitoring Network (KVN) Tamna Radio Observatory is located in Seogwipo on Jeju Island.  Also, Yonsei University is located in Seoul and Ulsan University is in Korea respectively.  Unit 4 is currently under construction at Seoul National University's Pyeongchang Campus. [사진=대덕넷DB]
Korea Satellite Radio Monitoring Network (KVN) Tamna Radio Observatory is located in Seogwipo on Jeju Island. Also, Yonsei University is located in Seoul and Ulsan University is in Korea respectively. Unit 4 is currently under construction at Seoul National University’s Pyeongchang Campus. [사진=대덕넷DB]

Korea completed KVN in 2008 and began to seriously observe space phenomena. At the time, leading countries like Japan were also initially skeptical of Korea. This is because obtaining and adjusting the signal takes a long time. However, contrary to expectations, KVN produced the same results as Japan in the first observation to verify the performance of the telescope. When the confirmed signals were made, the correct image appeared.

Since then, KVN has been used for research since 2010. At that time, international event horizon surveys focusing on the United States, Germany and Spain were underway, and Korea, China and Japan provided sightings that could complement M87 and black. centered on the Milky Way as major research topics. Then, in 2017, a campaign was launched in which 8 telescopes in 6 regions could participate at the same time, and Korea was invited to participate. This was the result of a previous search.

says Dr. Filho, “The telescope has the disadvantage of being difficult to observe because of the water vapour. But I wasn’t sure, so I couldn’t try. So I tried Korea and got KVN for the first time in the world. ”

He added: “KVN can monitor multiple frequencies and create images at the same time. It is a great innovation where one telescope performs multiple functions.

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