The magnetic field of a black hole was photographed for the first time

The scientists observed the black hole in the center of the galaxy M87 that was photographed about three years ago by optical means, and now the huge magnetic field around it has been photographed which reveals what happens when matter approaches the speed of light and part of it is swallowed up by the black hole. The writer is one of the scientists who participated in the project

By: Ziri Younisi, UKRI Stephen Hawking Fellow, UCL. Translation: Avi Blizovsky

There was great excitement when the International Event Horizon Telescope Collaboration showed the world the first ever image of a black hole in April 2019. It weighs 6.5 million times the mass of our Sun and is located in the galaxy M87, about 55 million light-years from Earth.

This was the first direct evidence that black holes exist. It also provided an extraordinary test of Einstein's theory of gravity and its basic concepts regarding space and time - testing gravity at its most extreme limits. But we still don't know much about these monsters.

Now, almost two years since this historic achievement, we have revealed a new image of M87 using a different technique. Our research, published in two new papers in The Astrophysical Journal Letters, provides important insights into the mysterious nature of black holes.

to see the invisible

Due to its distance from us, photographing this black thread is very challenging. It requires a resolution sharp enough to focus on an orange on the surface of the moon, or to be able to see individual atoms in a finger. The telescope succeeded in this thanks to an unprecedented collaboration between scientists around the world, which linked eight ground-based radio telescopes and turned the Earth into one giant virtual radio telescope.

Black holes are perhaps the most mysterious objects in nature, driving some of the most energetic and unobservable phenomena in our universe. Because of their event horizon, the limit beyond which nothing, not even light, can escape, we cannot see a black hole directly. But matter falling towards a black hole is pulled by its enormous gravitational pull and becomes extremely hot and luminous.

As it approaches the event horizon, this gas heats up greatly due to friction, moves close to the speed of light, and emits large amounts of radiation. It is radiation in the form of radio waves produced by this gas moments before it crosses the event horizon that the telescope is designed to detect.

A new look

The photograph of M87's black hole provided overwhelming support for the idea that supermassive black holes lurk in the cores of most (if not all) galaxies. They are the glue that holds the galaxies together and control their dynamics and evolution. But it is not clear how they work.

The new photo uses polarized light - light waves that tend in only one direction - produced by material at the edge of the black hole. Unpolarized light consists of light waves that oscillate in many different directions. Light can be polarized if it travels through hot and highly magnetized regions of space. The strong magnetic fields around the black hole are such regions, and by studying the properties of this polarized light we can learn much more about the material that produced it.

The new polarized image provides compelling new evidence for how strong magnetic fields around black holes can launch concentrated jets of charged gas stretching thousands of light years. We now think that such energetic and bright jets, which launch huge amounts of matter into the intergalactic medium, are attached to black holes through these strong magnetic fields.

Astronomers have built different models to explain how matter behaves near the black hole to better understand the process of jet formation, but they still do not know how jets larger than the galaxy itself can be launched from its central region, nor do we know exactly how the matter enters the black hole. Now we find that only theoretical models that show strongly magnetized matter can explain what is seen in the event horizon.

Our observations provide new and detailed information about the structure of the magnetic fields just outside the black hole. Not only do they bring us closer to understanding how black holes produce these mysterious and powerful jets, but also explain how extremely hot matter can hide outside a black hole, and persist despite its gravity. Our research suggests that the magnetic fields are strong enough to push the hot gas back and help it overcome the black hole's gravity.. Only the gas that slips through the field can begin to flow inward to the event horizon.

As exciting as these new polar images of the M87 black hole are, this is still just the beginning for the Event Horizon Telescope and black hole imaging science collaboration. We are already working on planning an observation and photograph of the black hole at the center of our galaxy, which we hope to publish later this year. Our galaxy's supermassive black hole located in Sagittarius A*.

Compared to M87, photographing the black hole in our galaxy is much more challenging to achieve. We are looking at the black hole through our own hazy, turbulent interstellar medium – there is a large amount of dust and gas in the way – making it significantly more difficult to take a clear picture. In the coming years, new telescopes will be added to the "Event Horizon" telescope array, both on Earth and in space and will ensure ever sharper images of black holes and provide a much more intimate understanding of these enigmatic entities.

There will be many more surprises in store. This is an exciting new era in humanity's exploration of the strong force of gravity and the nature of space and time, and without a doubt the best yet to come.

For an article in The Conversation

More of the topic in Hayadan:

• Record-breaking black holes discovered in massive galaxies
• Things that Yaorim know: where does the compass needle point?
• Black hole sounds

• A first-of-its-kind photograph of a black hole at the center of a galaxy has been achieved thanks to an international collaboration

• Why is photographing the black hole such a special event?