Today, astronomers announced that they have at last managed to capture an image of one of the most elusive objects in the universe: a black hole.
The image shows a black hole enveloped by a ring of light at the heart of Messier 87, a giant elliptical galaxy in the nearby Virgo Galaxy Cluster. The black hole itself lies at a distance of 55 million light-years and has a mass 6.5 billion times that of our Sun.
This was the outcome of an international collaboration which combined the observing power of eight ground-based radio telescopes. This result will lead to further discovery and allow astronomers to gain valuable insight into the nature of black holes and their immediate environment.
The Event Horizon Telescope (EHT) — a planet-scale array of eight ground-based radio telescopes forged through international collaboration — was designed to capture images of a black hole. In coordinated press conferences across the globe, EHT researchers revealed that they succeeded, unveiling the first direct visual evidence of the supermassive black hole in the centre of Messier 87 and its shadow. The shadow of a black hole seen here is the closest we can come to an image of the black hole itself, a completely dark object from which light cannot escape. The black hole’s boundary — the event horizon from which the EHT takes its name — is around 2.5 times smaller than the shadow it casts and measures just under 40 billion km across. While this may sound large, this ring is only about 40 microarcseconds across — equivalent to measuring the length of a credit card on the surface of the Moon. Although the telescopes making up the EHT are not physically connected, they are able to synchronize their recorded data with atomic clocks — hydrogen masers — which precisely time their observations. These observations were collected at a wavelength of 1.3 mm during a 2017 global campaign. Each telescope of the EHT produced enormous amounts of data – roughly 350 terabytes per day – which was stored on high-performance helium-filled hard drives. These data were flown to highly specialised supercomputers — known as correlators — at the Max Planck Institute for Radio Astronomy and MIT Haystack Observatory to be combined. They were then painstakingly converted into an image using novel computational tools developed by the collaboration.
