Jacinta Bowler
A purple smear from a nearby radio galaxy might not look like much, but it’s given scientists an exciting world first. The image shows the shadow of the supermassive black hole at the centre of the Messier 87 (M87) galaxy, along with a powerful jet launching out of it.
“Previously, we had seen both the supermassive black hole and the jet far away from it in separate images, but now with the new image we have taken a panoramic view of the black hole together with its jet in a new observing band,” says Dr Ru-Sen Lu from the Shanghai Astronomical Observatory in China.
Black holes are pretty well known for doing a lot of swallowing up stuff, but they can also produce incredibly powerful astrophysical jets. These are explosion-like beams of ionised matter that can travel close to the speed of light.
But these jets are still relatively mysterious. Scientists knew that the jets are coming from the black holes, but how this happens is still mostly a mystery.
The new image can’t tell us everything, but it does show the base of the jet connecting with the matter swirling around the black hole – which has never been seen before.
“This new image completes the picture by showing the region around the black hole and the jet at the same time,” adds Jae-Young Kim from the Kyungpook National University in South Korea and the Max Planck Institute for Radio Astronomy in Germany.
The team did this by mostly using the Global Millimetre VLBI Array (GMVA), as well as the phased Atacama Large Millimetre/submillimetre Array, and the Greenland Telescope to analyse the black hole in the 3.5 mm radio wavelength.
This is a little different to how the Event Horizon Telescope first imaged a black hole a few years ago. They used 1.3 mm, which shows the ring like structure around the black hole. However, the 3.5 mm radio image shows the dense radio core.
This different wavelength also showed that the black hole’s shadow had a bigger ring than the Event Horizon Telescope found.
“With the greatly improved imaging capabilities of the GMVA, we have gained a new perspective. We do indeed see the triple-ridged jet that we knew about from earlier VLBI observations,” says Dr Thomas Krichbaum of the Max Planck Institute for Radio Astronomy.
“But now we can see how the jet emerges from the emission ring around the central black hole and we can measure the ring diameter also at another wavelength.”
Of course, this isn’t the end of the story. The team is hoping to continue to unravel exactly how the jets are launched from the black hole in even more detail.
“The next steps in the high-resolution studies of M87 address the study of the radio colour of the jet and black hole shadow, as well as polarisation measurements, which will reveal the magnetic field,” says Dr Jae-Young Kim, from Kyungpook National University in Daegu, South Korea.
The research has been published in Nature.