A microquasar (jet object) that led scientists to identify a natural particle accelerator.
Scientific communication laboratory for MPIK/HESS
- Recent research has revealed how celestial bodies send accelerated particles into space.
- Jets from quasars and supernovae can send dangerous cosmic rays to Earth.
- For the first time, research has revealed how cosmic rays are accelerated to the speed of light.
Tiny black holes are helping scientists understand how mysterious cosmic rays travel through space and crash into Earth at nearly the speed of light.
High-energy cosmic rays are constantly raining down from space, but scientists don’t know much about them. One of the long-standing mysteries is how cosmic rays reach Earth at such speeds.
Researchers studying black holes have discovered for the first time a natural particle accelerator that accelerates cosmic rays raining down on our planet.
“In recent years we have been able to say, ‘Yes, we have particle accelerators. It’s hard to explain, but we have particle accelerators,'” said study author Max Planck of Heidelberg, Germany. Laura Olivera-Nieto, a researcher at the Max-Planck-Institut für Kernphysik, told Business Insider.
“We are now entering an era where we can actually answer the where and the how.”
An illustration showing how the jet around SS433 inserts itself into the Manatee Nebula.
Scientific communication laboratory for MPIK/HESS
High-speed cosmic rays coming from exploding black holes and stars
Our planet swims in a sea of cosmic rays. These charged particles bounce around the universe, providing a lot of energy.
If cosmic rays fell unfiltered onto our planet, life on Earth would not be possible. Cosmic rays travel at nearly the speed of light and have enough energy to destroy our DNA as they pass through our bodies.
An image of cosmic ray astronomy to clarify ultrahigh energy phenomena.
OSAKA METROPOLITAN UNIVERSITY/KYOTO UNIVERSITY/RYUUNOSUKE TAKESHIGE
Luckily, Earth’s atmosphere protects us from the worst radiation. But as more countries invest in putting humans on other planets in the future, it’s important to understand how radiation manifests itself in space.
And one thing we don’t really understand is how cosmic rays reach those speeds.
Look at the center of the jet
When scientists observe cosmic rays coming from quasars or supernovae, they usually see only large clusters.
High-energy cosmic rays come from quasars so far away (if they were close they would explode the galaxy) that it is difficult to see their details. Supernovae may be closer, but their low energy makes them too faint to be seen by telescopes on Earth.
But a nearby object called SS 433 offers a rare opportunity to peer into cosmic rays in unprecedented detail.
SS 433 is a microquasar, a tiny black hole with a mass about 10 times that of the Sun. It is located in the Manatee Nebula, a cloud of gas left behind by an exploding star about 18,000 light-years away.
“They’re called microquasars because they’re like miniature versions of them,” Olivera-Nieto says.
SS 443 is located in the Manatee Nebula (W50).
NASA
This means it is weak enough to survive nearby, but strong enough to emit particles with higher energies than a supernova.
There’s another reason this microquasar is “special,” Olivera-Nieto says. These objects normally have spurts for only a day or two.
“This jet has been running for 50 years. It’s the only celestial body we know of that has stopped in some sort of state.”
When Olivera-Nieto and his colleagues examined the object, they found a large gap in the jet. A small vortex was visible around the black hole about 0.1 parsec (about 0.326 light-years) away, but then nothing was visible and the jet reappeared about 75 light-years away.
Scientists think this gap is where particles are accelerated to the speed of light.
Video image of jets around SS433
The position of the throttle suggests how it works
Scientists have three hypotheses to explain how this natural particle accelerator works.
One possibility is that the magnetic field lines around the black hole carry these particles, and that the magnetic field lines experience such a strong strain that they break violently, sending the particles flying into space.
But in that case the accelerator would be much closer to the black hole.
Another possibility is that the black hole creates a tunnel that gives the particles a push as they bounce off the sides. But in that case, the particles would gradually become faster.
This observation supports the third hypothesis for the first time. The hypothesis is that the particles hit an invisible wall, a so-called discontinuity, which suddenly stops the particle in its tracks. This change in speed builds up energy around the particle, giving it that speed when it finally breaks through.
The question now is: what is creating this barrier?
“We don’t know. What’s really interesting is that this phenomenon is symmetrical,” Olivera-Nieto said.
“That means it’s somehow connected to the system itself.”
The research findings were published in the peer-reviewed academic journal Science.
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