A black hole is an enormous amount of matter so dense that it creates a gravitational field strong enough that even light cannot escape it. Although scientists have made various theoretical drawings and predictions about what a black hole looks like, it was not until this past Wednesday that scientists were able to obtain an actual image of one.
On Wednesday, scientists from the Event Horizon Telescope Organization announced they had captured an image of a black hole located in the Messier 87 galaxy, almost 55 million light years away from earth.
Prof. Paul Teukolsky, Hans A. Bethe Professor of physics and astrophysics, and Prof. Dong Lai, astronomy, expressed their enthusiasm about how this development can influence and advance the gravitational wave research being done at Cornell.
The image of the black hole is the “first direct image of this central engine that can power violent events at the center of a galaxy,” according to Teukolsky, which confirmed the model that astrophysicists have been using for a long time. The model suggests that most galaxies have massive black holes at their centers, and the nearby gas accreting onto the black hole gets heated and radiates light and radio waves.
This breakthrough was a culmination of efforts by hundreds of scientists as part of the Event Horizon Telescope project, which uses eight radio telescopes around the globe in an array to function together as one system.
“This observation was extremely difficult, since the diameter of the black hole is very small compared with its distance. The challenge was like reading the date on a quarter in Los Angeles from Ithaca,” Teukolsky said.
Being able to photograph the black hole is not a new technique in radio astronomy, but the measurement of the black hole is “one of the most advanced ever made,” according to Teukolsky.
Lai hopes that “this is only the beginning” in the field of black hole imaging. By adding more telescopes to the array, “we can better resolve the shape of the shadow … [and] study the behavior of this gas and how it moves around the black hole.”
Both Lai and Teukolsky are also excited by the developments being made in black hole research here at Cornell.
Lai said astronomers and physicists at Cornell are studying the merger of smaller black holes, which get orbit around and get closer and closer to each other. As a result, the orbit between the small black holes shrinks and two black holes merge into one.
Teukolsky also elaborated on Cornell’s use of data from the Laser Interferometer Gravitational-Wave Observatory.
“LIGO detects signals from the inspiral and merger of two black holes orbiting each other. Our group at Cornell solves Einstein’s equations on supercomputers to predict the details of the signals that LIGO should see, and our predictions are used to help analyze the data,” Teukolsky said.
Teukolsky believes that the discoveries by the Event Horizon Telescope “will help nail down what is really going on with accreting black holes at the centers of galaxies” and that its impact reaches far beyond just the scientific.
“One shouldn’t neglect the psychological impact of this image: Many people, including some physicists, have been reluctant to accept that such a bizarre object as a black hole can exist,” Teukolsky said. “But when you look at the image, you really do see orbiting gas … and in the middle, it’s black.”
“It’s an exciting time to study black holes,” Lai said. “We are only at the beginning of black hole research.”