First-Ever Image of a Black Hole Revealed
By: Andrea Reinhardsdottir
July 18, 2019
The first direct image of a black hole, M87, was compiled by eight radio x-ray
telescopes on four different continents and released to the world on April 4th, 2019.
The Event Horizon Telescope project (EHT) gathered a team of over 200 scientists operating the x-ray telescopes in Chile, Antarctica, Hawaii, Mexico, Arizona, Spain, France, and Greenland to capture enough data that made an identifiable image of the supermassive
black hole in the center of galaxy Messier 87, also known as called NGC 4486.
Even though M87 is around 55 million light years away from earth, the EHT team
speculates that it is exceptionally massive, estimated to be 6 billion times the size of our sun and 4 times the diameter of our solar system.
Simulation of the Black Hole Image
The EHT project utilized the Chandra X-Ray Orbital Satellite Observatory to obtain the initial data showing the existence of the black hole. Scientists were able to collect enough data to make out an image of M87 over two years of gathering data, and since a black hole doesn’t actually produce any light, scientists did not capture a “real” image of the black hole, instead they used additional X-ray radio telescopes in Chile, Antarctica, and Hawaii over a long period of time to capture enough data from the radiation and heat coming from around the black hole’s region.
The most common types of a black holes are the “stellar black holes”, that are created when a star with at least 20 times the mass of our sun dies out, causing it to collapse on its own endlessly, making the gravitational pull to be so great that even light cannot escape its pull.
However, M87 is much larger than a stellar black hole, it is a supermassive black hole. Scientists do not know how these black holes are formed, but there are speculations that every galaxy has one at its center. At the center of the Milky Way Galaxy, where the Earth resides, is a black hole known as, Sagittarius A*. Plans are being formed to photograph that black hole in the foreseeable future.
The light surrounding M87 is matter, which is suspected being bent by gravity around this black hole and is accelerating so rapidly around M87 that it heats up to hundreds of millions of degrees. Then with the help of some of our best supercomputers, and our brightest computer scientists, we were finally able to make out an image of the supermassive black hole, M87.
But this process was not easy...
There were 5 steps taken to get the first image of the black hole. First, they had to set up the telescopes around the globe to match up with one another and used atomic clocks so the recordings could be matched and put together perfectly.
The second step was gathering all the data from the telescopes, which was extremely difficult as one of the telescopes was on Antarctica and the other seven were in completely different parts of the globe. The total data is five petabytes, which is equal to the amount of data stored in the entire selfie collections over the lifetimes of more than 40,000 adolescents.
The third step was the correlation; here they condensed their data into terabytes instead of petabytes, a much smaller size, and making the data much easier to process.
The fourth step was to speed up the processing of the massive data files so the image could be organized in days instead of weeks. The process in scientific terms is called "fringe fitting".
Finally, there was the imaging step. They gave four teams all the data they needed, and instead of making everyone use one algorithm together to develop the image, each team was told to choose whatever algorithm they felt would work best. Then the teams submitted their work, and as it turns out, even though these teams used completely different algorithms to make out an image from the data, they found that all the images
looked extremely similar to one another.
This image was a huge step for physicists, and a crucial moment in their careers. Not only was M87 a huge advance in science, but also a very important factor in testing the theory of general relativity, one of Albert Einstein’s biggest accomplishments that he authored in 1915.
The Event Horizon Telescope Press Conference that revealed the first image of M87