New fiery doughnut image is our most detailed glimpse of a black hole

We have been given our most detailed look at a black hole yet, thanks to an update to the world’s first image of a black hole, taken one year later.

In 2019, researchers released an image of the supermassive black hole known as M87*, which is 55 million light years away at the centre of galaxy M87. That image, the world’s first glimpse of a black hole, was taken by a network of radio observatories around the world called the Event Horizon Telescope (EHT), during its first observation run in 2017.

Now, the EHT collaboration has released a follow-up image of M87*, taken during a 2018 observation run that used an additional telescope in Greenland.

The light in the image isn’t coming out of the black hole because, as the name suggests, these objects don’t emit light. Instead, what you can see is the silhouette of the black hole at the centre of a mass of hot matter that the black hole is pulling inwards with its powerful gravity.

“This image is telling us the story that the black hole shadow is persistent, it is still there,” says EHT scientist Eduardo Ros. “We see that the ring is a beautiful circle. It’s very circular, it’s not an ellipse or something else. In this ring we also see an enhancement in the south, which is what we expected.”

This enhancement, which can be seen as a slightly brighter glow below M87*’s shadow, which has shifted slightly, is due to distortions in space-time – described by Albert Einstein’s general theory of relativity – as the black hole rotates.

The resolution of the image is slightly better thanks to the additional telescope, which vastly improves the amount of data that can be cross-referenced against observations from other telescopes. However, non-ideal weather made for challenging observational conditions, says Ros, which means that the resolution isn’t as high as it theoretically could have been.