Famous Black Hole Shows Its Wobbly Past in New Movie
The release of the first-ever image of a real black hole in 2019 was a watershed moment for science, but there’s still more work to do. The Event Horizon Telescope (EHT) team is still planning future observations, but it’s also looking at old data to strengthen our understanding of how black holes work. The fruit of that labor is a short movie showing the evolution of the now-famous black hole over the past decade.
Black holes are the collapsed remains of massive stars, and they were predicted by Einstein’s general relativity long before we ever found evidence of them. However, we could only infer the presence of the black hole from X-ray emissions and gravitational effects. Imaging the supermassive black hole at the center of the M87 galaxy in 2019 (based on data from 2017) was an incredible accomplishment and yet more confirmation of general relativity.
The ETH team intends to conduct more observations of M87 and the central black hole of our own galaxy yearly in March or April. That’s when conditions are likely to be best for the network’s numerous telescopes around the world. However, the project was put on hold this year due to the COVID-19 pandemic. Instead, the team dug through old data on M87 to create images of its evolution over the past decade.
The new animation of the black hole’s wobbly past comes from the old data, plus the mathematical model developed for the famous 2019 image. The result involves a little more guesswork than the last one — the earlier data didn’t have enough resolution for imaging the black hole, but it was consistent with the data acquired in 2017. So, it was possible to plug it into the existing model to get an idea of how M87 has changed over time.
This animated GIF (above) shares several important features with the 2019 still. As expected, the central zone is dark because that’s where the event horizon is — anything that crossed that boundary is lost forever to the singularity’s crushing gravity. Around that is a bright ring known as the accretion disk where matter heats up as it spirals inward. One side of the ring is brighter than the other because one side (the bright one) rotates toward us and the other rotates away.
Interestingly, the animation shows that bright section moving around quite a lot over the past decade. This could be due to small changes in the disk’s rotation that reinforce or cancel out the brighter regions. This might be normal for a black hole of this size, but we won’t know until the team has a chance to conduct more observations in 2021 and beyond.