For the First Time in History - International Team including Members from Japan Captures the Shadow of Black Hole 55 Million Light Years Away Updated in June 2019

On April 10, an international team of researchers announced simultaneously at 6 spots around the world, that for the first time in history, the team had successfully photographed the shadow of a gigantic black hole located at the center of our galaxy, 55 million light-years away from the Earth. The team includes researchers from Japan’s National Astronomical Observatory (NAOJ). 8 radio telescopes around the world were linked together and the obtained data resulted in “directly verifying the existence of a gigantic black hole and its shadow through a photographic image─for the first time in history.”

The team consisted of about 200 researchers from different countries including Japanese researchers at the Mizusawa VLBI (Very Long Baseline Interferometry) Observatory in Iwate prefecture. The project itself is called the Event Horizon Telescope (EHT) project. The team succeeded in a vast collaborative plan to coordinate and combine observation data obtained from 8 radio telescopes spread out in 6 locations around the globe: the ALMA* and APEX telescopes in Chile, IRAM 30-meter Telescope in Spain, the James Clerk Maxwell Telescope in Hawaii, the Large Millimeter Telescope in Mexico, the Submillimeter Array in Hawaii, the Submillimeter Telescope in Arizona and the South Pole Telescope. The team started observation on April 2017, focusing on the huge black hole at the center of the M87 galaxy within the constellation Virgo, 55 million light-years away from Earth. Next, the team produced the final image from enormous high-resolution data obtained through all the radio telescopes. *The ALMA (Atacama Large Millimeter submillimeter Array) telescope in Chile is operated by a team including NAOJ.

As a result, the gas around the huge black hole shone out like a ring and the center of the ring stood out like a black shadow. The diameter of the ring is 100 billion kilometers and the mass of the black hole is about 6.5 billion times the size of the sun.

The black hole is an astronomical body with extremely high density and strong gravity. It is a dark body that absorbs everything. Even light cannot escape its darkness. Some astronomers have been trying to uncover the black hole and have observed X-rays emitted by gases being absorbed by the black hole. According to the international team, it was the first time they were able to directly prove its existence.

“What the EHT team captured is equivalent to 3 million times the vision of the human eye; like being able to look at a golf ball placed on the surface of the moon,” the international team explained. The ground-breaking result backs up Einstein's theory of relativity. Not only will the results help to unveil mysteries of the black hole, but may unravel the process of how stars and galaxies are formed. It is such a ground-breaking accomplishment that can affect the history of our universe.

The very image revealed by the international team: the shadow of a gigantic black hole at the center of the M87 galaxy (Provided by National Astronomical Observatory of Japan and the international research team─Credit: EHT Collaboration)

A sideways view of light traveling towards the earth. We can see that light cannot reach some parts inside the circled area, which is the shadow of the black hole (Provided by Nicolle R. Fuller/NSF, EHT Collaboration)