Home Science First image of a black hole ejecting a jet of matter

First image of a black hole ejecting a jet of matter

First image of a black hole ejecting a jet of matter

Most galaxies harbor a supermassive black hole at their center. While these objects are known to gobble up matter in their immediate vicinity, they can also hurl powerful jets of matter that extend beyond the galaxies they live in. This phenomenon has long been unknown in astronomy.

“We know that jets are ejected from the region around black holes, says Ru-Sen Lu of the Shanghai Astronomical Observatory in China, “but in fact, we still don’t fully understand how this happens. To study it directly, we need to observe the jet’s origin as close as possible to the black hole.”

The image shows for the first time the launch of a jet of matter close to a supermassive black hole

Precisely, a new image published this Wednesday shows for the first time: how the base of a jet connects with the matter that revolves around a supermassive black hole. The protagonist is the galaxy M87, located 55 million light years away in our cosmic neighborhood, and home to a black hole 6,500 million times more massive than the Sun and the first to be ‘photographed’.

“We conclude yet another important chapter in the study of M87, by obtaining the first glimpse of how its central black hole feeds on its accretion disk and launches the cosmic jet that was first observed more than a century ago”, says José. Luis Gómez, IAA-CSIC researcher who participated in the discovery.

Previous observations managed to obtain separate images of the region near the black hole and the jet, but this is the first time the two have been observed together. “Now, by showing the region around the black hole and the jet at the same time, we already have the complete picture”, adds Jae-Young Kim, from Kyungpook National University (South Korea) and the Max Planck Institute for Radio Astronomy. (Germany).

The image was obtained with the Global Millimetre VLBI Array (GMVA), the Atacama Large Millimeter/submillimeter Array (ALMA) and the Greenland Telescope (GLT), forming a global network of radio telescopes that have worked together as a virtual telescope of the size of the land. Such a large grid can discern very fine detail in the region around M87’s black hole.

Now, showing the region around the black hole and the jet at the same time, we have the full picture.

Jae-Young Kim of the Max Planck Institute for Radio Astronomy

The new image shows the jet emerging close to the ancient star, as well as what scientists call the black hole’s shadow. As matter orbits the region, it heats up and emits light. The black hole bends and captures some of that light, creating a structure around it that looks like a ring from Earth.

The darkness at the center of the ring is the shadow of the black hole, which was first imaged by the Event Horizon Telescope (EHT) in 2017. Both this new image and that one combine data obtained from several radio telescopes around the world, but the image now posted shows radio light emitted at a longer wavelength than EHT: 3.5 mm instead of 1.3 mm.

The jet emerges from the emission ring around the central supermassive black hole.

Thomas Krichbaum of the Max Planck Institute for Radio Astronomy

“At this wavelength, we can see the jet emerging from the emission ring around the central supermassive black hole,” said Thomas Krichbaum of the Max Planck Institute for Radio Astronomy.

The ring size observed by the GMVA network is approximately 50% larger compared to the Event Horizon Telescope image. “To understand the physical origin of the larger and thicker ring, we had to use computer simulations to test different scenarios,” explains Keiichi Asada of Academia Sinica in Taiwan. The results suggest that the new image reveals that there is more material falling towards the black hole than could be observed with the EHT.

The massive black hole jet is seen rising from the center of the black hole. / S. Dagnello (NRAO/AUI/NSF)

These new observations of M87 were made in 2018 with the GMVA, which consists of 14 radio telescopes in Europe and North America. In addition, two other facilities have been linked to the GMVA: the Greenland Telescope and ALMA, of which ESO is a partner. ALMA is made up of 66 antennas in the Chilean Atacama Desert and played a key role in these observations. Data collected by all these telescopes around the world are combined using a technique called interferometry, which synchronizes the signals picked up by each individual facility.

It is necessary to have a network of telescopes distributed all over the planet to observe a star well.

But to properly capture the true shape of an astronomical object it is important that telescopes are spread across the Earth. The GMVA’s telescopes are mainly aligned east to west, so the addition of ALMA in the southern hemisphere was essential to capture this image of the jet and shadow of the black hole of M87. “Thanks to ALMA’s location and sensitivity, we were able to reveal the black hole’s shadow and at the same time get a deeper look at the jet’s emission,” explains Lu.

In the future, observations with this network of telescopes will continue to unravel how powerful jets can be launched by supermassive black holes. “We plan to observe the region around the black hole at the center of M87 at different radio wavelengths to study the jet’s emission in more depth”, confirms Eduardo Ros, from the Max Planck Institute for Radio Astronomy.

These simultaneous observations would allow the team to unravel the complicated processes that occur near the supermassive black hole. “The next few years will be exciting as we may learn more about what is happening near one of the most mysterious regions in the universe,” concludes Ros.

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