An international team of researchers that the Korea Astronomical Institute is joining has confirmed the appearance of an “accretion disk” of a black hole in the “M87” galaxy, located 54 million light-years from Earth, and published it in the scientific journal “Nature” on Wednesday. An accretion disk refers to gas emitting light while being sucked into the black hole by its strong gravity. This is the first time that an accretion disk has been observed.
The researchers precisely analyzed the black hole, which was first observed by humans in 2019, using a telescope with longer wavelengths. The international team used the International Millimeter Very Large Array (GMVA), the Atacama Large Millimeter and Submillimeter Radio Interferometer (ALMA) in Chile, and the Greenland Telescope (GLT), which has a wavelength of 3.5 millimeters, longer than that of the EHT.
Longer wavelengths allow observations of the same object to cover a wider range of its surroundings. This is why previous observations showed only a "photon ring" around the black hole, while the latest observations showed the light from the larger accretion disk.
The researchers also captured the black hole's shadow and jet at the same time. Jets are rapid flows of gas and liquid emitted by the interaction of the black hole, the magnetic field, and the accretion disk around the black hole. In the image of the black hole released by the researchers, a violet-colored jet can be seen spewing out of the black hole. The researchers explained that the high velocity of the jet could influence the evolution of stars and galaxies far away from the black hole.