Black hole ‘accelerators’ cause mysterious cosmic rays to rain down on us at the speed of light

Black hole ‘accelerators’ cause mysterious cosmic rays to rain down on us at the speed of light

An artist’s impression shows a microquasar that allowed scientists to locate a natural particle accelerator.
Scientific Communication Laboratory for MPIK/HESS

  • Research has revealed how space objects send accelerated particles through space.
  • Jets from quasars and supernovae can send dangerous cosmic rays hitting Earth.
  • For the first time, a study has shown that cosmic rays are accelerating close to the speed of light.

A tiny black hole is helping scientists understand how mysterious cosmic rays can travel through the universe and hit Earth at nearly the speed of light.

High-energy cosmic rays are constantly raining down on us from space, but scientists don’t know much about them. One of the long-standing mysteries is how cosmic rays can reach our planet so quickly.

For the first time, researchers peering into a black hole have discovered a naturally occurring particle accelerator that accelerates the cosmic rays that bombard our planet.

“Over the years, we could have said, ‘Yes, there is particle acceleration.’ How? It is impossible to say. But there is,” Laura Olivera-Nieto, a researcher at the Max Planck Institute for Kernphysik in Heidelberg, told Business Insider.

“Now we’re entering a period of where and how we can respond,” he said.

Artist’s impression shows how the jets around SS 433 align with the Manatee Nebula.
Scientific Communication Laboratory for MPIK/HESS

Fast cosmic rays come from black holes and exploding stars

Our planet is swimming in a sea of ​​cosmic rays. These charged particles orbit the universe and carry a lot of energy with them.

If these rays had not filtered into our planet, life on Earth would not be possible. Cosmic rays travel at almost the speed of light—so fast that they can pass through our bodies like air—and carry so much energy that our DNA breaks into ribbons.

Artist’s rendering of ultra-high-energy cosmic ray astronomy to clarify extremely energetic events.
OSAKA METROPOLITAN UNIVERSITY/KYOTO UNIVERSITY/RYUUNOSUKE TAKESHIGE

Thankfully, our planet’s atmosphere protects us from the worst effects of radiation. But it’s still important for us to understand what this looks like in our universe, especially as more countries invest in turning humans into a multiplanetary species in the future.

One of the things we don’t really understand is how they get to the speeds they do.

Looking into the heart of a jet

When scientists look at cosmic rays from quasars and supernovae, what they usually see is just a big blob.

High-energy cosmic rays come from very distant quasars – any closer and they’ll blow up the Milky Way, so they’re hard to see in detail. Supernovae may be nearby, but they send out low-energy beams that are really faint when seen through a telescope on Earth.

But a nearby space object called SS 433 provided a rare opportunity to view cosmic rays in unprecedented detail.

SS 433 is a microquasar, that is, a small black hole about ten times the mass of the sun. It is located in the Manatee Nebula, a cloud of gas left by an exploding star about 18,000 light-years away.

“It’s called a microquasar because it looks like a miniature version of these things,” Olivera-Nieto said.

SS 443 is located within the Manatee Nebula, about 74 light-years from Earth.
NASA

This means that it is weak enough to be nearby, but powerful enough to eject particles with higher energies than a supernova.

There’s another reason this microquasar is so “special,” Olivera-Nieto said. These facilities usually have jets that last a day or two.

“This plane has had jets for 50 years, which is unusual because it’s the only plane we know of that has been stuck in one position,” he said.

When Olivera-Nieto and his colleagues looked at this object, they noticed a large gap in the planes. They could see tiny spirals around the black hole about 0.1 parsec away, then nothing, and the jets reappeared about 75 light-years away.

Scientists believe that space is where particles accelerate near the speed of light.

The location of the accelerator tells us how it works

Scientists have three theories to explain how this natural particle accelerator works.

One is that the magnetic field lines around the black hole carry these particles, and they become so strained that they violently tear apart, sending the particles into space.

But in this case, the accelerator would be quite close to the black hole.

Another is that the black hole creates tunnels that amplify particles as they bounce off the sides. But then the particles would get faster and faster.

For the first time, the observation favors a third hypothesis: the particles run into an invisible wall, a so-called discontinuity, that abruptly stops particles in their tracks.

This change in speed causes energy to build up around the particles, which eventually gives them this speed as they pass.

Now the question is: what is causing this shock?

“We don’t know because it’s quite interesting because it happens symmetrically on both sides,” Olivera-Nieto said

“So that means it’s kind of connected to the system itself,” he said.

The study was published in a scientific research journal.

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