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The acceleration of cosmic-ray protons in the supernova remnant RX J1713.7–3946

Abstract

Protons with energies up to 1015 eV are the main component1 of cosmic rays, but evidence for the specific locations where they could have been accelerated to these energies has been lacking2. Electrons are known to be accelerated to cosmic-ray energies in supernova remnants3,4, and the shock waves associated with such remnants, when they hit the surrounding interstellar medium, could also provide the energy to accelerate protons. The signature of such a process would be the decay of pions (π0), which are generated when the protons collide with atoms and molecules in an interstellar cloud: pion decay results in γ-rays with a particular spectral-energy distribution5,6. Here we report the observation of cascade showers of optical photons resulting from γ-rays at energies of 1012 eV hitting Earth's upper atmosphere, in the direction of the supernova remnant RX J1713.7–3946. The spectrum is a good match to that predicted by pion decay, and cannot be explained by other mechanisms.

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Figure 1: Differential fluxes, and distributions of the image orientation angle α (inset).
Figure 2: Multi-band emission from RX J1713.7-3946, and emission models.
Figure 3: Profile of emission around the northwest rim of RX J1713.7-3946.
Figure 4: Allowed regions in the parameter space defined by peak flux (E2dF/dE) plotted against peak energy.

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References

  1. Simpson, J. A. Elemental and isotopic composition of the galactic cosmic-rays. Annu. Rev. Nucl. Part. Sci. 33, 323–381 (1983)

    Article  ADS  CAS  Google Scholar 

  2. Pohl, M. Proc. 27th Int. Cosmic Ray Conf. (Hamburg) 2001, Rapporteur talk (eds Simon, M., Lorenz, E. & Pohl, M.) (Copernics Gesellschaft e.V., Katlenburg-Lindau, Germany, in the press); also as preprint astro-ph/0111552 at http://xxx.lanl.gov (2001)

  3. Koyama, K. et al. Evidence for shock acceleration of high-energy electrons in the supernova remnant SN1006. Nature 378, 255–258 (1995)

    Article  ADS  CAS  Google Scholar 

  4. Tanimori, T. et al. Discovery of TeV gamma rays from SN 1006: Further evidence for the supernova remnant origin of cosmic rays. Astrophys. J. 497, L25–L28 (1998)

    Article  ADS  CAS  Google Scholar 

  5. Aharonian, F. A., Drury, L. O'C. & Völk, H. J. GeV/TeV gamma-ray emission from dense molecular clouds overtaken by supernova shells. Astron. Astrophys. 285, 645–647 (1994)

    ADS  CAS  Google Scholar 

  6. Naito, T. & Takahara, F. High energy gamma-ray emission from supernova remnants. J. Phys. G 20, 477–486 (1994)

    Article  ADS  CAS  Google Scholar 

  7. Pfeffermann, E. & Aschenbach, B. in Roentgenstrahlung from the Universe (eds Zimmermann, H. H., Trünmper, J. & Yorke, H.) 267–268 (MPE Report 263; Max-Planck-Institut fuer Extraterrestrische Physik, Garching, 1996)

    Google Scholar 

  8. Koyama, K. et al. Discovery of non-thermal X-rays from the northwest shell of the new SNR RX J1713.7–3946: The second SN 1006? Publ. Astron. Soc. Jpn 49, L7–L11 (1997)

    Article  ADS  Google Scholar 

  9. Muraishi, H. et al. Evidence for TeV gamma-ray emission from the shell type SNR RXJ1713.7–3946. Astron. Astrophys. 354, L57–L61 (2000)

    ADS  Google Scholar 

  10. Slane, P. et al. Nonthermal X-ray emission from the shell-type supernova remnant G347.3-0.5. Astrophys. J. 525, 357–367 (1999)

    Article  ADS  CAS  Google Scholar 

  11. Hillas, A. M. in Proc. 19th Int. Cosmic Ray Conf. (La Jolla) Vol. 3, 445–448 (NASA Conference publication, 1985)

    Google Scholar 

  12. Tanimori, T. et al. in Proc. 27th Int. Cosmic Ray Conf. (Hamburg) (eds Simon, M., Lorenz, E. & Pohl, M.) Vol. 6, 2465–2468 (Copernics Gesellschaft e.V., Katlenburg-Lindau, Germany, 2001)

    Google Scholar 

  13. Aharonian, F. A. & Atoyan, A. M. On the origin of TeV radiation of SN 1006. Astron. Astrophys. 351, 330–340 (1999)

    ADS  CAS  Google Scholar 

  14. Mastichiadis, A. & de Jager, O. C. TeV emission from SN 1006. Astron. Astrophys. 311, L5–L8 (1996)

    ADS  CAS  Google Scholar 

  15. Yoshida, T. & Yanagita, S. Proc. 2nd INTEGRAL Workshop ‘The Transparent Universe’ 85–88 (ESA SP-382 European Space Agency, Noordwijk, Netherlands, 1997)

    Google Scholar 

  16. Naito, T., Yoshida, T., Mori, M. & Tanimori, T. Radio to TeV gamma-ray emission from SN 1006 and shock acceleration around its rim. Astron. Nachr. 320, 205–206 (1999)

    Article  ADS  CAS  Google Scholar 

  17. Tomida, H. Synchrotron Emission from the Shell-like Supernova Remnants and the Cosmic-Ray Origin Thesis, Kyoto Univ. (1999)

    Google Scholar 

  18. Butt, Y. M., Torres, D. F., Combi, J. A., Dame, T. & Romero, G. Is the supernova remnant RX J1713.7-3946 a hadronic cosmic ray accelerator? Astrophys. J. 562, L167–L171 (2001)

    Article  ADS  CAS  Google Scholar 

  19. Ellison, D. C., Slane, P. & Gaensler, B. M. Broad-band observations and modeling of the shell-type supernova remnant G347.3-0.5. Astrophys. J. 563, 191–201 (2001)

    Article  ADS  Google Scholar 

  20. Hartman, R. C. et al. The third EGRET catalog of high-energy gamma-ray sources. Astrophys. J. Suppl. 123, 79–202 (1999)

    Article  ADS  Google Scholar 

  21. Rybichi, G. B. & Lightman, A. P. Radiation Processes in Astrophysics (Wiley and Sons, New York, 1979)

    Google Scholar 

  22. Mathis, J. S., Mezger, P. J. & Panagia, N. Interstellar radiation field and dust temperatures in the diffuse interstellar matter and in giant molecular clouds. Astron. Astrophys. 128, 212–229 (1983)

    ADS  CAS  Google Scholar 

  23. Walsh, A. J., Hyland, A. R., Robinson, G. & Burton, M. G. Studies of ultracompact HII regions—I. Methanol maser survey of IRAS-selected sources. Mon. Not. R. Astron. Soc. 291, 261–278 (1997)

    Article  ADS  CAS  Google Scholar 

  24. Aharonian, F. A., Atoyan, A. M. & Kifune, T. Inverse Compton gamma radiation of faint synchrotron X-ray nebulae around pulsars. Mon. Not. R. Astron. Soc. 291, 162–176 (1997)

    Article  ADS  Google Scholar 

  25. Sikora, M., Begelman, M. C. & Rees, M. J. Comptonization of diffuse ambient radiation by a relativistic jet: The source of gamma rays from blazars. Astrophys. J. 421, 153–162 (1994)

    Article  ADS  Google Scholar 

  26. Enomoto, R. et al. Design study of CANGAROO-III, stereoscopic imaging atmospheric Cherenkov telescopes for sub-TeV gamma-ray detection. Astropart. Phys. 16, 234–244 (2002)

    Article  ADS  Google Scholar 

  27. Enomoto, R., et al. in Proc. 27th Int. Cosmic Ray Conf. (Hamburg) (eds Simon, M., Lorenz, E. & Pohl, M.) Vol. 6, 2477–2480 (Copernics Gesellschaft e.V., Katlenburg-Lindau, Germany, 2001)

    Google Scholar 

  28. Aharonian, F. A. et al. The energy spectrum of TeV gamma rays from the Crab nebula as measured by the HEGRA system of imaging air Cerenkov telescopes. Astrophys. J. 539, 317–324 (2000)

    Article  ADS  Google Scholar 

  29. Ishizaki, Y. . Spectra and Large-scale Isotropy of the Cosmic X-ray Background from ASCA observations Thesis(Univ. Tokyo

Download references

Acknowledgements

We thank H. Tomida for help in understanding the ASCA observational results, M. Seta for comments on molecular cloud density, and F. Aharonian for suggestions. This work was supported by a Grant-in-Aid for Scientific Research by the Japan Ministry of Education, Science, Sports and Culture, and the Australian Research Council.

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Enomoto, R., Tanimori, T., Naito, T. et al. The acceleration of cosmic-ray protons in the supernova remnant RX J1713.7–3946. Nature 416, 823–826 (2002). https://doi.org/10.1038/416823a

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