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The acceleration of cosmic-ray protons in the supernova remnant RX J1713.7-3946
R Enomoto1, T Tanimori, T Naito
1Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan. enomoto@icrr.u-tokyo.ac.jp
Nature
|April 27, 2002
Summary
Scientists observed high-energy gamma-rays from supernova remnant RX J1713.7-3946, matching the predicted pion decay signature. This provides evidence that supernova remnants accelerate protons to cosmic ray energies.
Area of Science:
- Astrophysics
- Particle Physics
Background:
- Protons up to 10^15 eV are primary cosmic rays, but their acceleration sites remain unidentified.
- Supernova remnants (SNRs) accelerate electrons to cosmic-ray energies.
- Shock waves from SNRs interacting with interstellar medium may accelerate protons.
Purpose of the Study:
- To identify the origin of high-energy cosmic ray protons.
- To investigate the particle acceleration mechanisms in supernova remnants.
Main Methods:
- Observed cascade showers of optical photons in Earth's upper atmosphere.
- Analyzed the spectral-energy distribution of gamma-rays.
- Focused observations towards the supernova remnant RX J1713.7-3946.
Main Results:
- Detected gamma-rays with energies around 10^12 eV.
- The observed gamma-ray spectrum closely matches the predicted signature of pion (pi^0) decay.
- The results are inconsistent with other known astrophysical mechanisms.
Conclusions:
- Supernova remnants are likely sites for proton acceleration to cosmic ray energies.
- Pion decay is confirmed as a source of high-energy gamma-rays from SNRs.
- Provides strong evidence linking SNRs to the origin of cosmic rays.
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