Radio Telescopes could take even Sharper Images of Black Holes

Astronomers believe that radio telescopes in space can take much better images of black holes in the future.

Black holes have always attracted a lot of attention, since their discovery in 1916. Recently, astronomers have finally captured the first-ever image of a black hole to put an end to the long-lasting anticipation. The Event Horizon Telescope observed the central black hole of a distant galaxy, called Messier 87. Following this development, the next challenge that scientists face is to improve the quality of such images in order to find physical evidence for Einstein’s Theory of General Relativity.

An international team of researchers has proposed the use of radio telescopes in space to achieve the desired results. The concept, known as the Event Horizon Imager (EHI), suggests that we should place 2-3 satellites in a circular orbit around the Earth to observe black holes. The study published in the journal ‘Astronomy & Astrophysics’ had simulated images of the black hole, Sagittarius A*, as if the radio telescopes were actually there. Freek Roelofs, the Lead Author of the paper who is seeking a Ph.D. at Radboud University, referred to the advantages of using radio telescopes in space and said,

“There are lots of advantages to using satellites instead of permanent radio telescopes on Earth, as with the Event Horizon Telescope (EHT). In space, you can make observations at higher radio frequencies, because the frequencies from Earth are filtered out by the atmosphere. The distances between the telescopes in space are also larger. This allows us to take a big step forward. We would be able to take images with a resolution more than five times what is possible with the EHT.”    

Theory of General Relativity

Researchers believe that sharper images of a black hole will provide extremely useful information for detailed testing of the theory of general relativity. Heino Falcke, a Professor of Radio Astronomy, mentioned that the movement of satellites makes for considerable advantages. He explained that they allow you to take near-perfect images to see the real details of black holes. Consequently, even if small deviations from Einstein’s theory occur, we should be able to see them. The involvement of EHI into the observation artillery will enable astronomers to image 5 additional black holes (smaller in size) that the EHT is unable to focus on.

Technological Difficulties

The researching team simulated different versions of the technology under different conditions and found that there are certain scientific challenges that need to be handled, despite the promising signs of the simulations. For the sake of determining the technical feasibility of these radio telescopes, they collaborated with scientists from ESA/ESTEC. Volodymyr Kudriashov, a member of ESA/ESTEC who is also associated with the Radboud Radio Lab, talked about the technical aspects of the project and said,

“The concept demands that you must be able to ascertain the position and speed of the satellites very accurately. But we really believe that the project is feasible. With the EHT, hard drives with data are transported to the processing center by airplane. That’s of course not possible in space.”

In this case, transfer of data is not possible through airplanes and it will be exchanged via a laser link. During this process, data will be partially processed on board before being sent back to Earth for detailed analysis. Kudriashov also mentioned that laser links are already installed in space which makes this concept even more feasible.

Combining Radio Telescopes with EHTs

Although the initial proposal revolves around the independent functioning of these satellites, astronomers are considering the idea of creating a hybrid system where orbiting radio telescopes are combined with the ones on Earth. Falcke mentioned the possibility of such a system in the following words:

“Using a hybrid like this could provide the possibility of creating moving images of a black hole, and you might be able to observe even more and also weaker sources.”