You’re looking at the centre of our galactic home, the Milky Way, as imaged by 64 radio telescopes in the South African wilderness. Scientists released this image today to inaugurate the completed MeerKAT radio telescope. But these scopes form part of an even more ambitious project: the Square Kilometer Array, a joint effort to build the world’s largest telescope, spanning the continents of Africa and Australia. This image shows filaments of particles, structures that seem to exist in alignment with the galaxy’s central black hole. It’s unclear what causes these filaments. Maybe they are particles ejected by the spinning black hole; maybe they are hypothesised “cosmic strings;” and maybe they’re not unique, and there are other, similar structures waiting to be found, according to a 2017 release from Harvard-Smithsonian Center for Astrophysics. “This image from MeerKAT is awesome to me because the fine filaments seen in the radio image are excellent tracers of the galactic magnetic field, something we don’t get to see in most optical and infrared data,” Erin Ryan, research space scientist at the NASA Goddard Space Flight Center, told Gizmodo. “High-resolution data like this will help the study of galactic magnetic fields and how they may be important for galaxy evolution.”
Each one of MeerKAT’s 64 radio receivers is a 44-foot radio antenna. They collect radio waves from cosmic sources (like the centre of the galaxy) with a timestamp, convert it to digital information, and send it to a central location. The information from each dish is then correlated together into an image. Imagine how a regular telescope works—light is collected by mirrors and focused in the centre. In this case, it’s as if each of the radio telescopes is itself a mirror, and the “centre” is where the fibre optic cables meet to create the main image. Ultimately, MeerKAT will form part of the larger Square Kilometer Array (SKA), named because it will have a square kilometre of collecting area, potentially with higher resolution than the Hubble Space Telescope in the radio band. By the late 2020s, it should consist of 2,000 radio dishes in the Karoo region of South Africa and Murchison Shire in Western Australia, and the total project could one day consist of 3,000 dishes in other African countries, reports South Africa’s News24. News24 reports that MeerKAT alone cost over $330 million (USD), while the total SKA cost hasn’t yet been determined. A telescope like this could have many important uses: perhaps it could measure the history of the Universe’s expansion to help understand the mysterious dark energy. It could also offer insight into the laws of gravity at the Universe’s largest scales, and more generally see details of our galaxy and Universe that are invisible to other telescopes. There are many cosmic mysteries yet to be solved. And some of the answers may come from an enormous array of dishes in South Africa and Australia.
Credit: Ryan F. Mandelbaum for Gizmodo, 13 July 2018.