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Dynamics of particles in the vicinity

11th European Space Weather Week. Recent Advances in Space Weather Science. Dynamics of particles in the vicinity of the heliospheric current sheet: observations versus theory Olga Khabarova  Valentina Zharkova  Gang Li.

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Dynamics of particles in the vicinity

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  1. 11th European Space Weather Week. Recent Advances in Space Weather Science Dynamics of particles in the vicinity of the heliospheric current sheet: observations versus theory Olga Khabarova  Valentina Zharkova  Gang Li Pushkov Institute of terrestrial magnetism and radiowave propagation (IZMIRAN), Russia University of Northumbria, Newcastle Upon Tyne, United Kingdom CSPAR, University of Alabama in Huntsville, USA habarova@izmiran.ru

  2. Olga Khabarova  Valentina Zharkova  Gang Li Outline • Behaviour of particles in a vicinity of reconnecting current sheets in the solar wind: • - theoretical points of view; PIC-modelling • - observations •  Theoretical aspects of particle acceleration due to magnetic island dynamics in the solar wind • Combination of theoretical ideas. An application of a new paradigm to explanation of observations.

  3. Acceleration of particles in current sheets with a guiding magnetic field: 2D3V PIC simulation Siversky, Zharkova, JPP, 2009; Zharkova,Gordovsky, ApJ, 2004; Zharkova,Agapitov, JPP, 2009

  4. Acceleration of particles in current sheets with a guiding magnetic field: 2D3V PIC simulation (Verboncouer & Gladd, 1995) Vinflow 0.01 Valfven Drift electric field In order to avoid numerical instabilities in the PIC code(Verboncoeur et al. 1995), the following constrains are to besatisfied Δt is the time step, Δξ is the grid step in any direction Siversky, Zharkova, JPP, 2009; Zharkova,Gordovsky, ApJ, 2004; Zharkova,Agapitov, JPP, 2009

  5. bounced proton transit proton Trajectories of electrons and protons near the reconnecting current sheet. midplain Proton trajectories are shown in red, and electron trajectories are shown in blue.

  6. Polarization electric field Separation of opposite charged particles around the current sheet leads to the occurrence of a strong electric field

  7. Particle acceleration in current sheets with a guiding magnetic field - application to the corona Siversky, T. V., & Zharkova, V. V. 2009, J.Plasma Phys., 75, 619

  8. Particle acceleration in current sheets with a guiding magnetic field - application to the corona HXR and γR imaging Possible evidence for sepration of opposite charged particles: flares 2.223 MeV footpoints (ions) on opposite sides of the flaringloop arcade are displaced from the corresponding 0.2–0.3 MeVfootpoints (electrons). Hurford et al., 2006 ApJ

  9. electrons protons Separation of opposite charged particles around the HCS. Direct evidence near the HCS HCS Zharkova, Khabarova, ApJ, 2012

  10. A regular structure of the heliospheric current sheet A 3D reconstructed velocity plot, from the viewpoint of a remote observer (STEL data).

  11. Acceleration of particles in current sheets with a guiding magnetic field: application to the solar wind Z (GSE) Z (GSE) (GSE) observations (model) X (GSE) X Y Y Z Z X Y (GSE) • The HCS is suggested to undergo acontinuous reconnection process. • The current sheet thickness is about a size of the proton gyroradius. The simulation region ismade larger by a factor of 10-100 to the both sides from the midplane. • The background magnetic field is stationary during the whole simulation. • Plasma particles in the PIC simulations are considered to generate their own electric and magnetic fields. Zharkova, Khabarova, Astrophysical Journal, 752, 1, 35(2012)

  12. Acceleration of particles in current sheets with a guiding magnetic field: application to the solar wind 10-6 Zharkova, Khabarova, ApJ, 2012; Khabarova, Zastenker, SolPh 2011

  13. Acceleration of particles in current sheets with a guiding magnetic field: application to the solar wind Crossing of a thin sector boundary, the 3-second Wind SWE 3DP data: a) IMF magnitude; b) the in-ecliptic component of the IMF (Bx, GSE); c) azimuthal angle of the IMF (φB); d-f) spectrograms of the electron flux at the energies of 370 eV, 84 eV and 27 eV, respectively, as a function of pitch angle. 340 eV 84 eV 27 eV Zharkova, Khabarova, ApJ, 2012

  14. Acceleration of particles in current sheets with a guiding magnetic field: application to the solar wind Density=100 cm-3 Bz0=10-8T By=0.1Bz0 Bx=-0.02Bzo Density=10 cm-3 Bz0=10-8T By=0.01Bz0 Bx=-0.02Bzo Density=100 cm-3 Bz0=10-9T By=0.01Bz0 Bx=-0.002Bzo Density=10 cm-3 Bz0=10-9T By=0.1Bz0 Bx=-0.02Bzo 10 cm-3 Zharkova, Khabarova, ApJ, 2012

  15. Acceleration of particles in current sheets with a guiding magnetic field: application to the solar wind The results can solve the problem of mismatches between polarity reversal signatures in suprathermal electron pitch angle spectrograms and changes of azimuth angle of the magnetic field. Kahler, Lin (Geophys. Res. Lett., 1994); Crooker, Kahler, Larson, Lin (J. Geophys. Res., 2004) The main idea of the [Zharkova & Khabarova, ApJ (2012)] paper: small- and medium-scale features of the IMF and plasma characteristics observed near the HCS may be explained simultaneously only if magnetic reconnection was assumed to occur simultaneously and re-currently in many places on the HCS.

  16. Can the magnetic reconnection accelerate particles to keV-MeV energies in the solar wind? Acceleration of particles in current sheets due to magnetic reconnection (Zelenyi et al., 2013; Drake et al. 2010, 2013; Büchner et al, 2010; Lapenta 2012 etc.). Energization of particles up to MeV in the Earth’s magnetotail [Zelenyi, Lominadze & Taktakishvili (1990); Ashour-Abdalla et al. (2011) ], but it is still disputable for the HCS, because of some lack of observations. It is furthermore believed that there no particle acceleration in the keV-MeV range is associated with the magnetic reconnection exhausts in the solarwind, i.e. there is no significant local acceleration at the reconnecting HCS [Gosling et al. (2005)]. Goldstein, Matthaeus & Ambrosiano (1986): the maximum energy achievable during the magnetic reconnection at the HCS should be ~100 keV. Zharkova & Khabarova (2012; 2014): the maximum energy achievable during the magnetic reconnection at the HCS may be ~ MeV.

  17. Drake et al, 1998, 1999, 2006, Daughton et al, 2011 Theory: magnetic island contraction and merging can accelerate particles Theory: tearing instability of current sheets leads to magnetic island formation • The dominant charged particle energization processesare • the electric field induced by magnetic island merging, • magnetic island contraction. • In both cases, the magnetic island topology ensuresthat charged particles are trapped in regions where they can experience repeatedinteractions with either the induced electric eld or contracting magnetic islands. Zank G.P., le Roux J.A., Webb G.M., Dosch A., & O. Khabarova. Particle acceleration via reconnection processes in the supersonic solar wind. Astrophysical Journal, V.797, 2014

  18. Combination of ideas: Zharkova & Khabarova, ApJ (2012) + Zank et al., ApJ (2014) Small-scalemagnetic island formation predominantly occurs near the HCS Particles can be accelerated at least to keV energies at the HCS and re-accelerated in dynamically changing magnetic islands near the HCS Cartwright, M. L., and M. B. Moldwin (2010), Heliospheric evolution of solar wind small-scale magnetic flux ropes. J. Geophys. Res., 115, A08102

  19. A specific form of the HCS (ripples on the HCS) is favorable for keeping magnetic islands and particle acceleration to high energies Small-scale magnetic islands in the solar wind and their role in particle acceleration. Part 1: Dynamics of magnetic islands near the heliospheric current sheet. Khabarova, Zank, Li, le Roux, Webb, Dosch, submitted to ApJ

  20. Support for the idea on re-acceleration of particles in magnetic islands ACE WIND ACE and WIND spacecraft were 150 Re apart. A clear magnetic field vector rotation is seen in magnetic islands, that occurs simultaneously with energetic particle flux increases Khabarova, Zank, Li, le Roux, Webb, Dosch, submitted to ApJ

  21. Support for the idea on re-acceleration of particles in magnetic islands Particle acceleration associated with islands near the HCS (an after -CME event) Khabarova, Zank, Li, le Roux, Webb, Dosch, submitted to ApJ

  22. Support for the idea on re-acceleration of particles in magnetic islands Magnetic reconnection a) at the leading edge of an ICME; b) behind the ICME

  23. Support for the idea on re-acceleration of particles in magnetic islands Particle acceleration associated with islands near the HCS (a pre-CME event) Khabarova, Zank, Li, le Roux, Webb, Dosch, submitted to ApJ

  24. Support for the idea on re-acceleration of particles in magnetic islands Particle acceleration associated with islands near the HCS (a pre-CME event) Khabarova, Zank, Li, le Roux, Webb, Dosch, submitted to ApJ

  25. Olga Khabarova (habarova@izmiran.ru) Valentina Zharkova Gang Li SUMMARY • The local energetic particle flux enhancements might be explained by particle energization occurring near the HCS during dynamical evolution of secondary current sheets and small-scale magnetic islands. • These structures are supposed to trap and re-accelerate particles (initially accelerated at the HCS) up to MeV/nucleon. • Effectiveness of this process depends on the topology of the HCS (ripples). • A magnetic reconnection is a re-currently ongoing process that takes place at the heliospheric current sheet (HCS) . • The separation of particles of the opposite sign during the magnetic reconnection at the HCS leads to strong particle acceleration Thank you for your attention!

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