A solitary image capturing both a supermassive black hole and its jet.

In May 2022, the Event Horizon Telescope (EHT) team released the first-ever radio image of the central black hole M87. It was an amazing discovery based on observations made with a worldwide array of radio telescopes. Recently, they re-released a newer, sharper image of the black hole’s “ring of light”.

Now, a team of astronomers from Europe, Korea and China has taken things a step further. This week, they shot another great sight of this beast, this time, in a slightly different range of radio emissions. It clearly shows the relationship between the supermassive black hole, its ring of light, and the famous high-speed jet.

This last image was taken using a wide array of radio telescopes. It consists of the Global Baseline Very Large Array (GMVA), the Atacama Large Millimeter Array (ALMA), and the Greenland Telescope (GLT). Their combined observations showed very small details in the region around the galactic core. It is the first time that the three main parts of an object are in the same image.

The observations, taken in 2018, show the area in radio light emitted at a longer wavelength than the EHT image. Its diameter is 3.5 mm instead of 1.3 mm. “At this wavelength, we can see how the jet exits the emission ring around the central supermassive black hole,” says Thomas Kirchbaum of the Max Planck Institute for Radio Astronomy. The material streaming away from M87 is an astrophysical jet. It contains a very hot (ionized) substance that flows at a high speed along the axis of rotation.

Get the big picture of a black hole

To understand the structures in the latest image, we need to know more about them. We know that supermassive black holes at the cores of galaxies are very powerful gravitational wells. Nothing can escape because they pretty much absorb everything in the neighborhood. The formation of these monsters is still not well understood. But we can observe what they do in their neighborhoods.

In the case of M87, there is an accretion disk that funnels matter into the black hole. On the other hand, the jet helps some materials to escape. Understanding how such a giant jet was created has been a long-standing problem in astronomy. It’s likely the result of some kind of activity within the surrounding accretion disk.

The jet formation is also likely to include entangled magnetic fields. However, astronomers are still not clear on all the details. “We know that jets shoot out from the region around black holes, but we still don’t fully understand how this actually happens,” said Ru-Sen Lu of the Shanghai Astronomical Observatory in China. “To study this directly we need to observe the jet’s origin as close as possible to the black hole.”

The new image also shows how the base of the jet is connected to the disk of matter spinning around the black hole. Previous observations have shown separate views of this disk and the plane. So, this is the first time that the two traits have been observed together. “This new image completes the picture by showing the region around the black hole and the jet at the same time,” said team member Jae-Yong Kim from Kyungbuk National University in South Korea and the Max Planck Institute for Radio Astronomy in Germany.

sounding ring

The ring of light surrounding M87’s supermassive black hole is another fascinating piece of the study. It is actually something of an optical illusion. As matter rotates around, it is heated by friction with other matter, and interaction with magnetic fields. This causes light to be emitted. The black hole’s powerful gravitational influence bends and captures some of the light. This creates what looks like a ring. We can see it in the EHT image of M87’s black hole.

The new observations for the episode were made in 2018 and are now being released along with a paper (below) that discusses the science. The ring size observed by the GMVA grid is approximately 50% larger compared to the EHT image. “To understand the physical origin of the larger, thicker ring, we had to use computer simulations to test different scenarios,” explained Keiichi Asada of Academia Sinica in Taiwan. The results indicate that the new image reveals more material falling toward the black hole than can be observed with the EHT.

More observations of M87’s black hole are planned

This new observation of the jet and its black hole is the system’s first next-generation view. Future studies will continue with networks of radio telescopes interconnected together. They will continue to investigate the relationship between black holes and their jets. “We plan to observe the region around the black hole at the center of M87 at different radio wavelengths to further study the jet’s emissions,” noted Eduardo Ross of the Max Planck Institute for Radio Astronomy.

Simultaneous observations using this matrix and the EHT will allow the team to decipher all of the complex actions that occur near the supermassive black hole. They will be interested not only in the aircraft, but also in the physics and activities of the accretion disk as the jet blasts off. “The coming years will be exciting, as we will be able to learn more about what is happening near one of the most mysterious regions in the universe,” Ross said.