EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

General Spectrum Fitting for Energetic Particles

Zixuan Liu1, Linghua Wang1, Haobo Fu1, Krucker Sam2, and Wimmer-Schweingruber Robert3
Zixuan Liu et al.
  • 1School of the earth and space science, Peking University, China
  • 2Space Sciences Laboratory, University of California, Berkeley, USA
  • 3Institute of Experimental and Applied Physics, University of Kiel, Germany

We propose a general fitting formula of energy spectrum of suprathermal particles, J=AE-β1[1+(E/E0)α](β1-β2)/α, where J is the particle flux (or intensity), E is the particle energy, A is the amplitude coefficient, E0 represents the spectral break energy, α (>0) describes the sharpness of energy spectral break around E0, and the power-law index β12) gives the spectral shape before (after) the break.  When α tends to infinity (zero), this spectral formula becomes a classical double-power-law (logarithmic-parabola) spectrum. When both β2 and E0 tend to infinity, this formula can be simplified to an Ellison-Ramaty-like equation. Under some other specific parameter conditions, this formula can be transformed to a Kappa or Maxwellian function. Considering  the uncertainties both in particle intensity and energy, we fit this general formula well to the representative energy spectra of various suprathermal particle phenomena including solar energetic particles (electrons, protons,  3He and heavier ions), shocked particles, anomalous cosmic rays, hard X-rays, solar wind suprathermal particles, etc. Therefore, this general spectrum fitting formula would help us to comparatively examine the energy spectrum of different suprathermal particle phenomena and understand their origin, acceleration and transportation.

How to cite: Liu, Z., Wang, L., Fu, H., Sam, K., and Robert, W.-S.: General Spectrum Fitting for Energetic Particles, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8189,, 2020


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