Skip to main content
SpringerLink
Log in

Hard X rays of relativistic electrons accelerated in solar flares

  • Published:
Geomagnetism and Aeronomy Aims and scope Submit manuscript

Abstract

The direction and polarization degree of hard X rays (HXRs) in solar flares are studied. The continuous injection of relativistic electrons, which is implemented in powerful flares, is considered. The stationary relativistic kinetic equation is studied by using the method of expansion in terms of the Legendre polynomial and by integrating the equations for the expansion coefficients. The HXR characteristics are calculated using the bremsstrahlung relativistic cross-section for different angular and energetic electron distributions in the acceleration region. A high linear polarization degree of HXRs (∼35%) has been obtained for narrow (∼cos6θ) beams of electrons with a soft spectrum (∼E −6); the polarization degree decreases with increasing quanta energy, whereas the directivity of a high-energy emission increases. This effect is absent for a nonrelativistic approximation. The considered model is applied to one of the most powerful flares in cycle 23, registered on October 28, 2003. The measured polarization degree values at relativistic energies (0.2–0.4 and 0.4–1 MeV) agree with the results achieved in the considered model when the electron energy spectrum index (δ = 2.5), angular distribution part (∼cos6θ), and the spectrum cutoff energy (E max = 1.3 MeV) were specified.

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

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Boggs, S.E., Coburn, W., and Kalemci, E., Gamma-Ray Polarimetry of Two X-Class Solar Flares, Astrophys. J., 2006, vol. 638, no. 2, pp. 1129–1139.

    Article  Google Scholar 

  • Charikov, Ju.E., Guzman, A.B., and Kudryavtsev, I.V., Hard X-Ray Emission of Solar Flares and Non-Stationary Kinetics of Electron Beams, Astron. Astrophys., 1996, vol. 308, pp. 924–928.

    Google Scholar 

  • Gluckstern, R.L. and Hull, M.H., Polarization Dependence of the Integrated Bremsstrahlung Cross Section, Phys. Rev., 1953, vol. 90, no. 6, pp. 1030–1035.

    Article  Google Scholar 

  • Guzman, A.B., Kudryavtsev, I.V., and Charikov, Yu.E., The Evolution of Electrons Accelerated in Solar and Stellar Flares and the Pulsed Structure of Hard X-Ray Radiation, Astron. Rep., 1996, vol. 40, no. 2, pp. 246–251.

    Google Scholar 

  • Kasparova, J., Kontar, E.P., and Brown, J.C., Hard X-Ray Spectra and Positions of Solar Flares Observed by RHESSI: Photospheric Albedo, Directivity and Electron Spectra, Astron. Astrophys., 2007, vol. 466, no. 2, pp. 705–712.

    Article  Google Scholar 

  • Kelner, S.R. and Skrynnikov, Y.I., Polarization and Directivity of Hard X-Ray Bremsstrahlung in Solar Flares, Soviet Astron., 1985, vol. 29, no. 4, pp. 445–448.

    Google Scholar 

  • Kontar, E.P., Brown, J.C., Emslie, A.G., et al., Deducing Electron Properties from Hard X-Ray Observations, Space Sci. Rev., 2011, vol. 159, no. 1–4, pp. 301–355.

    Article  Google Scholar 

  • Kotov, Yu.D., Glyanenko, A.S., Arkhangelsky, A.I., et al., Experimental Study of Parameters of X-Ray Radiation from Solar Flares Using the PENGUIN-M Instrument aboard the CORONAS-PHOTON Spacecraft, Sol. Syst. Res., 2011, vol. 45, no. 2, pp. 135–145.

    Article  Google Scholar 

  • Krucker, S., Battaglia, M., Cargill, P.J., et al., Hard X-Ray Emission from the Solar Corona, Astron. Astrophys. Rev., 2008, vol. 16, pp. 155–208.

    Article  Google Scholar 

  • Leach, J. and Petrosian, V., The Impulsive Phase of Solar Flares. I. Characteristics of High Energy Electrons, Astrophys. J., 1981, vol. 251, no. 1, pp. 781–791.

    Article  Google Scholar 

  • Matveev, G.A. and Charikov, Yu.E., Distribution of Hard X-Ray Bursts over the Solar Disk Registered from March to May 1979, Soln. Dannye, 1984, no. 1, pp. 96–100.

  • Suarez-Garcia, E., Hajdas, W., Wigger, C., Arzner, K., Gudel, M., Zehnder, A., and Grigis, P., X-Ray Polarization of Solar Flares Measured with Rhessi, Sol. Phys., 2006, vol. 239, no. 1–2, pp. 149–172.

    Article  Google Scholar 

  • Zharkova, V.V., Brown, J.C., and Syniavskii, D.V., Electron Beam Dynamics and Hard X-Ray Bremsstrahlung Polarization in a Flaring Loop with Return Current and Converging Magnetic Field, Astron. Astrophys., 1995, vol. 304, p. 284.

  • Zhitnik, I.A., Logachev, Yu.I., Bogomolov, A.V., et al., Polarization, Temporal, and Spectral Parameters of Solar Flare Hard X-Rays as Measured by the SPR-N Instrument onboard the CORONAS-F Satellite, Sol. Syst. Res., 2006, vol. 40, no. 2, pp. 93–103.

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Ioffe Physical-Technical Institute, Russian Academy of Sciences, Politekhnicheskaya ul. 26, St. Petersburg, 194021, Russia

    I. V. Kudryavtsev & Yu. E. Charikov

  2. Central Astronomical (Pulkovo) Observatory, Russian Academy of Sciences, Pulkovskoe sh. 65, St. Petersburg, 196140, Russia

    I. V. Kudryavtsev

  3. St. Petersburg State Polytechnical University, Politekhncheskaya ul. 29, St. Petersburg, 195251, Russia

    Yu. E. Charikov

Authors
  1. I. V. Kudryavtsev
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Yu. E. Charikov
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to I. V. Kudryavtsev.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Kudryavtsev, I.V., Charikov, Y.E. Hard X rays of relativistic electrons accelerated in solar flares. Geomagn. Aeron. 52, 875–882 (2012). https://doi.org/10.1134/S0016793212070080

Download citation

  • Received:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1134/S0016793212070080

Keywords

Search

Navigation