Nearly five years ago, the world got its first glimpse of a black hole thanks to the Event Horizon Telescope (EHT), a collaboration of radio telescopes around the globe. Now, the EHT team has released a second image of the supermassive black hole M87*, located at the center of the Messier 87 galaxy 55 million light-years away. While the new image looks similar to the original, it provides valuable data that reinforces our understanding of black holes and general relativity.
The new image, captured in 2018, shows the familiar black-hole shadow: a dark region surrounded by a glowing ring of hot gas and dust swirling around the black hole. This is exactly what scientists expected to see based on Einstein's theory of general relativity. The strong gravity bends light around the black hole, creating the dark region where light cannot escape. The hot gas and dust, however, emit light that forms the glowing ring.
The new image is not an exact replica of the first one. The brightest part of the ring has shifted slightly, likely due to the turbulent flow of matter around the black hole. However, the overall size and shape of the ring remain the same, confirming the predictions of general relativity.
While seeing a picture of a black hole is exciting, the real significance of this new image lies in its independent confirmation of the first image. Having two separate sets of data that produce the same image strengthens our understanding of black holes and general relativity.
Researchers at Caltech, including Professor Katherine (Katie) L. Bouman, Nitika Yadlapalli Yurk, and Aviad Levis, played a key role in the imaging of M87*. Bouman is a coordinator of the EHT Imaging Working Group and was instrumental in developing the algorithms that assemble the EHT's data into an image. Yurk, a recent Caltech PhD graduate, contributed to the development of synthetic data used to test the imaging algorithms. Levis, a postdoctoral research associate, helped explore different image candidates.
The EHT team is now working on even more sensitive telescopes and imaging techniques to capture even better pictures of black holes. These future observations will help us unravel even more mysteries about these fascinating objects.
This new image of M87* is a testament to the power of international collaboration and cutting-edge technology. It provides valuable data that will continue to shape our understanding of the universe and its most extreme objects.