Advertisement

Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Polarization of hard X-rays from solar flares

Abstract

The polarization of hard solar X-radiation (> 10 keV) is calculated on the assumption that electrons get a non-isotropic velocity distribution in the initial phase of a flare. The brems-strahlung generated by nonthermal electrons spiralling around magnetic field lines with discrete pitch angles is considerably polarized if observed at approximately right angles to the magnetic field. In the energy range from 10 to 50 keV the degree of polarization is not strongly dependent on the photon energy. For pitch-angle distributions of the form sin2α and cos2α, the polarization has opposite signs; it decreases appreciably at high photon energies. The observation of X-ray polarization will be useful in deducing the physical conditions in flares.

This is a preview of subscription content, log in to check access.

References

  1. Benz, A. O. and Gold, T.: 1971, Solar Phys. 21, 157.

  2. Cline, T. L., Holt, S. S., and Hones, E. W., Jr.: 1968, J. Geophys. Res. 73, 434.

  3. Elwert, G.: 1939, Ann. Phys. 34, 178.

  4. Elwert, G.: 1968, in K. O. Kiepenheuer (ed.), ‘Structure and Development of Solar Active Regions’, IAU Symp. 35, 444.

  5. Elwert, G. and Haug, E.: 1970, Solar Phys. 15, 234.

  6. Elwert, G. and Haug, E.: 1971, Solar Phys. 20, 413.

  7. Gluckstern, R. L., Hull, M. H., and Breit, G.: 1951, Science 114, 480.

  8. Gluckstern, R. L. and Hull, M. H.: 1953, Phys. Rev. 90, 1030.

  9. Holt, S. S. and Ramaty, R.: 1969, Solar Phys. 8, 119.

  10. Kane, S. R. and Anderson, K. A.: 1970, Astrophys. J. 162, 1003.

  11. Korchak, A. A.: 1967, Soviet Phys.-Dokl. 12, 192.

  12. May, M. M.: 1951, Phys. Rev. 84, 265.

  13. Schnopper, H. W. and Kalata, K.: 1969, Astron. J. 74, 854.

  14. Tindo, I. P., Ivanov, V. D., Mandel'stam, S. L., and Shuryghin, A. I.: 1970, Solar Phys. 14, 204.

  15. Vaiana, G. S. and Giacconi, R.: 1969, in D. G. Wentzel and D. A. Tidman (eds.), Plasma Instabilities in Astrophysics, Gordon and Breach, Science Publishers, p. 91.

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Haug, E. Polarization of hard X-rays from solar flares. Sol Phys 25, 425–434 (1972). https://doi.org/10.1007/BF00192340

Download citation

Keywords

  • Magnetic Field
  • Flare
  • Energy Range
  • Photon Energy
  • Initial Phase