Since Einstein first hypothesized the existence of black holes in his 1915 Theory of General Relativity, there has been no visual proof of their existence. It is impossible to take a picture of the actual black hole as no light can escape the event horizon, but a picture can be taken of the light that bends around the black hole.To do this, telescopes from all across the world joined to create the Event Horizon Telescope, a virtual Earth-sized radio dish. These telescopes working together were able to obtain a sharper image than any of the observatories working alone. The black hole pictured is labeled as “supermassive”, weighing in at 6.5 billion times the mass of our sun and sits in the center of the M87 galaxy, in the Virgo constellation. To give some perspective, the galaxy held together by this black hole is 980,000 light years in diameter compared to the Milky Way, which is only 100,000 light-year diameter. This supermassive black hole is 55 million light-years away, so the Event Horizon telescope’s resolution had to be better than any other telescope. One factor that determines resolution is the diameter of the dish, the Event Horizon Telescope was able to achieve an Earth-sized diameter to get the high resolution necessary to take the quality picture.
With the extreme precision of the Event Horizon Telescope, there is still one aspect of the black hole that scientists are interested in which the telescope was unable to capture, called high-energy jet matter. This high energy matter that comes from the black hole is hypothesized to be powered by the spinning of the black hole. Since the formation of supermassive black holes is still an open field of research the cause of the rotation is unknown. Researchers are confident that the black hole is spinning due to the asymmetry of the glow in the picture captured by the telescope. Although the telescope does not have a high enough sensitivity to capture an image of the jet itself or the jet forming region, further advancements may actually show this fascinating and currently invisible phenomenon.
This image provides further evidence that the Theory of General Relativity developed by Einstein and the contents of the center of galaxies is correct. The image of the supermassive black hole is at the center of a galaxy and distinctly shows the bending light around the event horizon. Six papers, published in The Astrophysical Journal Letters, have been released documenting the way that these scientists were able to create the image shown today. Smaller black holes have been studied and shown to have three properties predicted by general relativity: spin, mass, and electric charge. These observations have been shown by smaller instruments such as the LIGO and Virgo gravitational wave detectors by measuring space time disturbances caused by black hole collision. Scientists are excited to look more at larger black holes to see if the same rules apply and find out any exceptions that can be detected.
“This is the only place in the universe where a knot is tied that cannot be untied, every other place in the universe you can, in theory, come back from, but not there.” Said Director Shepard Doeleman, the head director of the Event Horizon Telescope. This supermassive black hole will continue to be observed by more telescopes to capture its changing motion in hopes of ultimately determining what’s causing those changes. This new information that will be obtained will further expand our understanding of the universe and these supermassive black holes at the center of galaxies.