Japanese astrophysicists have seen dim flickers of visible light from a black hole. They have added that the light could be visible to anyone with a moderate-size telescope.
In a study, which was published in the Nature journal, and performed by the researchers from the RIKEN laboratory, Rochester Institute of Technology, Kyoto University, space agency JAXA, and Hiroshima University, it was observed that the nearby V404 Cygni black hole binary is so luminescent, that even amateur stargazers can spot it using a 20 cm backyard telescope.
Mariko Kimura, lead author of the study, said, “Black hole binaries are far from Earth. Light from near them disappears in its long journey to Earth because it is absorbed into interstellar matter. However, we have found that activity in the vicinity of a black hole can be observed in optical light at low luminosity for the first time. These findings suggest that we can study physical phenomena that occur in the vicinity of the black hole using moderate optical telescopes without high-spec X-ray or gamma-ray telescopes.”
In their study, the astrophysicists analyzed V404 Cygni. It is a binary system that is composed of a black hole about nine times the mass of our sun and a companion star slightly less massive than the sun. It is about 7,800 light-years away from Earth in the constellation Cygnus, the swan. V404 Cygni possesses one of the closest black holes to Earth.
The system was dormant for 26 years. However, they detected an outburst of X-rays from V404 Cygni in 2015 that lasted for about two weeks. This activity from the accretion disk of V404 Cygni’s black hole briefly made it one of the brightest sources of X-rays seen in the universe. After this outburst, the astrophysicists spotted flickering visible light from V404 Cygni. Its fluctuations varied over time-scales of 100 seconds to 150 minutes.
According to the astrophysicists, this black hole is visible through a backyard telescope because the X-ray radiation heats up the outer rim of the disk. This disk is emitting high quantities of optical rays, which are visible without the need of specialized equipment. The researchers added that this phenomenon can be seen from several locations around the world.