ALBUQUERQUE, N.M. — Invisible black holes throughout the fabric of space-time have been the stuff of science fiction books and movies for decades.
They are fiction no more. On Wednesday a team of scientists released the first image of a supermassive black hole, showing a dark ring defining the hole, surrounded by the event horizon, a fiery orange of superheated gas and dust where some light can still escape.
The image was made using radio telescopes linked across the globe, creating an earth-sized telescope named the Event Horizon Telescope. Contributing research was conducted by staff at the National Radio Astronomy Observatory, which runs the Very Large Array west of Socorro.
Chris Carilli, an astrophysicist and chief scientist whose NRAO office is on the Socorro campus of New Mexico Tech, said imaging the black hole is one of the top breakthroughs in physics in the last 30 years and “is certainly right up there with the Nobel Prize-winning results of the discovery of gravity waves.”
It also represents “a truly a major leap forward in our understanding of the universe.”
A black hole generally occurs when the gravity of a star causes it to collapse in on itself, Carilli explained. “The gravity is so strong that not even light can escape. That happens out to a certain distance where gas and dust surrounding the hole begins falling in, gaining energy and getting superheated to about 1 million degrees.”
That material emits light, some of which is able to escape and is what allows the radio telescopes to see the point-of-no-return outline of the black hole.
This particular supermassive black hole is at the center of a galaxy called Messier 87, or M87, which is about 55 million light years from earth, Carilli said. “So the light we’re seeing right now from the black hole was actually emitted 55 million light years from earth,” allowing us to look back in time.
A light year is the distance that light, traveling at just over 186,000 miles per second, covers in one year.
The black hole at the center of M87 has a mass that’s 6.5 billion times greater than the mass of our sun, he said. And while our sun has a diameter of just under 1 million miles, the diameter of the black hole is about 20 billion miles — spanning a distance that’s greater than our own solar system.
Albert Einstein in 1915 theorized that structures in the universe have gravitational mass, which bends and warps the fabric of space-time, as well as light. The imaging of the M87 black hole is the ultimate proof of Einstein’s theory, Carilli said.
“The phenomenon they’re seeing in the black hole is exactly the same,” Carilli said. “Space-time and light are being bent, but being bent so severely that they fall right into the black hole.”
Creating the Event Horizon Telescope involved connecting, synchronizing and processing radio frequency data from eight telescope arrays around the world, including the Atacama Large Millimeter Array, or ALMA, in Chile.
The NRAO is funded in large part by the National Science Foundation. “We design, build and operate large radio telescopes,” Carilli said.
The NRAO’s two major facilities are the VLA and ALMA. The VLA was not part of the Event Horizon Telescope because it does not operate in the right frequency range, he said. ALMA, however, was the “anchor element” of the Event Horizon Telescope.
“The key to the Event Horizon Telescope was the extraordinary spatial resolution, and the ability to see really, really small things,” Carilli said. “The analogy is if there was a chile field on the moon and you had the image resolution to see each individual chile.”
The Event Horizon Telescope Project cost an estimated $50 million to $60 million, with about $26 million coming from the National Science Foundation.
Hundreds of terabytes of telescope data was gathered two years ago and over a period of four days, when weather conditions around the world met specific criteria. An international team of more than 200 scientists and researchers from 20 countries were involved in the project, which was led by Sheperd Doeleman of Harvard.
Although Carilli was not directly involved in the Event Horizon Telescope, many staff people at the NRAO played important roles in building ALMA.
He highlighted the work of astrophysicist Ralph Marson, whose name appears on the published discovery paper, and who did much of the core computer programming. He also pointed to astrophysicist Craig Walker, whose name does not appear on the discovery paper, and who did much of the early groundwork and research on the M87 galaxy, where the black hole was located, as well as research into the powerful jets of high energy particles and magnetic fields coming from the black hole, he said.
The NRAO is now developing a major proposal to the National Science Foundation to expand the VLA in Socorro, which is about 40 years old. The proposed new facility would have 10 times the capacity of the current VLA and would likely come with a cost of about $2 billion.
“There’s a lot of good science that can be done in small research labs, but certain breakthroughs can only be achieved with a major investment,” Carilli said. “If you want to see the origins of the universe, if you want to image a black hole, you need to make that major investment. Advances of this type are not just scientific, but sociological. They help to place humanity in the greater context of the cosmos.”