scorecardA mesmerizing photo shows powerful magnetic fields swirling around a black hole
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A mesmerizing photo shows powerful magnetic fields swirling around a black hole

Aria Bendix   

A mesmerizing photo shows powerful magnetic fields swirling around a black hole
LifeScience3 min read
A view of the M87 supermassive black hole in polarized light.    EHT Collaboration
  • Scientists recently captured a black hole's powerful magnetic fields on camera.
  • The image shows that these magnetic fields are strong enough to keep some matter from falling in.
  • Matter that doesn't get sucked in gets launched back into space in the form of jets.

When scientists published the first photo of a black hole in 2019, the image looked more like a smudge than a detailed snapshot. But a new photo released Wednesday offers a sharper view of the powerful magnetic fields that loop around the black hole's inner edge.

Since 2009, scientists from the international Event Horizon Telescope (EHT) Collaboration have been observing the black hole at the center of the super-giant Messier 87 (M87) galaxy, which is about 54 million light-years from Earth.

Most matter that gets close to the edge of a black hole gets sucked into the event horizon - the boundary after which the black hole's gravity is so strong that anything, including light, gets devoured. But some particles manage to escape the abyss and instead get launched into space in the form of jets that extend far beyond the galaxy's edge.

Before their new research was published on Wednesday, the EHT scientists knew that magnetic fields played some role in ejecting matter from this black hole and others like it.

"The open question from the first image [in 2019] was exactly what the structure of those magnetic fields were and how strong they are," Andrew Chael, a NASA Hubble Fellow at the Princeton Center for Theoretical Science, told Insider.

After observing the new image, the scientists discovered that the magnetic fields surrounding M87's black hole are actually quite strong - around 2 to 50 times stronger than Earth's magnetic field.

"They sort of build up onto the black hole and push back against the gas that's falling in," Chael said. "Some of the gas falls in, but some of it is accelerated by the magnetic fields out to really large distances."

m87 galaxy
Messier 87 as seen through a telescope.      ESO

Clues from light

Chael said he was pleasantly surprised by the level of detail revealed in the new photo.

"One of the things we all expected from the first images was that it might be really hard to interpret them," he said.

His team was able to analyze the black hole's magnetic fields because of the light emitted by the black hole's accretion disk, or outer ring of hot matter. When this matter encounters a strong magnetic field, the light waves become polarized - meaning they prefer to travel in a certain direction.

Polarized light is therefore a glaring indicator that magnetic fields are present. By observing the direction of this light in their images, the EHT scientists were able to map the magnetic field lines - and ultimately estimate their strength.

Their new research marks the first time that astronomers have been able to measure polarization this close to the edge of a black hole.

More telescopes will help with future black-hole investigations

black hole jet
M87's jet in polarized light.      ALMA (ESO/NAOJ/NRAO), Goddi et al.

The EHT scientists used a global network of eight telescopes to capture their first image of M87's black hole. Chael said the group is adding more telescopes to its lineup in hopes of eventually collecting video.

Such footage may reveal the black hole's motion as it spews particles into space.

"As it launches material out into this jet, can we see the dynamics of what's happening?" Chael said. "Can we trace movies of material as it's ejected along these field lines? That's one of the big goals in the coming years."

At the very least, scientists should be able to get a clearer picture of the black hole's large jet, which spans several thousand light-years. Right now, Chael said, the jet appears dim in images as it gets further away from the black hole.

"Something we'd really like to be able to do is see the base of the jet in the image," Chael said. "If we had a few more telescopes in our array, we should be able to see that."