For the first time, there is light being released from the black hole, as astronomers have observed. According to reports, there were flashes of light coming from a black hole in the constellation of Cygnus, about 7,800 light years away from earth.
These flashes of light lasted from a few minutes to a few hours. As observed even by a moderately powerful telescope from earth, just measuring around 20-cm, the discovery was intriguing as it defied the laws of physics concerning black holes. According to basic knowledge and NASA, it would be virtually impossible for supermassive black holes to give off any light. This is true as theoretically a black hole will always swallow matter including light.
According to the actual observers of the phenomenon, particularly Kyoto University astronomer and lead researcher, Mariko Kimura, such an activity in the vicinity of the black hole would be observable only in optical light with low luminosity.
However, one explanation that Kimura advanced regarding the presence of light coming from the black hole is the formation of accretion disks near the black hole’s event horizon. Accretion disks are formed whenever whole stars are ripped apart by black holes. Stream of plasma can therefore result from the process.
The streams of plasma would then hit temperatures as high as 10 million degrees Celsius within the event horizon. This may then give off a bright glow within the black hole. The bright glow is then mistaken as light that escapes from the black hole. Although the light was first detected by NASA’s Swift space telescope, it was the Japanese researchers who tracked the light.
With 26 locations around the world having their telescopes directed at V404 Cygni, the light was then confirmed. As published in Nature magazine, the Japanese team hypothesized that light originated from the X-rays emitted from the center of the accretion disk. The X-rays caused the emission of optical rays as they irradiated and heated up.
According to NASA, a possible explanation for the light is coronas near black holes. Coronas produce X-ray light because of its highly energetic particles. In the case of a lamppost model of coronas, the coronas themselves are considered compact sources of light just like light bulbs. These “light bulbs are located around the black hole and so are mistaken as a part of it.
Coronas may produce lights that erupt as flares and whose level of brightness is similar to the one detected recently from Cygnus. A similar discovery was documented in 2007 as well as in 2014, although the lights during these times were similar to that of a flare.
One more explanation, according to John Gaustad, Swarthmore College professor of astronomy and physics, although light cannot escape from the black hole, matter that falls into a black hole can turn extremely hot. Thus, the heating that ensues produces lots of light and radiation as matter itself falls into the black hole.
There are several more explanations as to why light seemed to have been emitted by the black hole. However, one thing is sure – all the theorists maintained that light could never escape it. Thus, the observed light may have either been a spark inside or something outside of it.