Scientists using data from NASA's Fermi mission
have pinpointed a “PeVatron,”
an elusive source of cosmic ray particles here.
Cosmic rays strike our atmosphere every day.
They're mostly protons, and come in a broad range of energies.
The highest-energy particles made within our own galaxy
exceed 1,000 trillion electron volts (PeV).
That's 10 times the energy reached by the world’s most powerful particle collider.
Locating PeV sources, or PeVatrons, isn’t easy.
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Like all cosmic rays, their paths to Earth become scrambled by magnetic fields.
But when these particles strike other matter,
they produce gamma rays,
high-energy light that travels straight to us.
This stellar wreckage
was already a prime PeVatron suspect.
Supernova remnant. PeVatron.
Gas cloud.
And with 12 years of Fermi data, the connection's even clearer.
About 10,000 years ago,
a powerful supernova exploded at this spot.
What remains now is a bright gamma-ray pulsar
and a blast wave that's still expanding into space.
Protons ensnared in this blast wave keep gaining energy
until they eventually break out.
They eventually hit the gas cloud,
producing the tell-tale gamma rays Fermi sees.
One PeVatron down. How many more are out there?
Multiwavelength image byJayanne English, University of Manitoba,NASA/Fermi/Fang et al. 2022,and Canadian Galactic Plane Survey/DRAO/FCRAO