Energetic particle fluxes at heliospheric shocks: Evidences of superdiffusion and comparison between analytical and numerical modeling

Prete, Giuseppe; Perri, S.; Zimbardo, G.

doi:10.1016/j.newast.2021.101605

Cited by 2 publications

(2 citation statements)

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“…This variability is also found in observations of energetic particles in the vicinity of Earth (see, e.g., Lee et al 2012). This can depend on several factors, such as the instrinc variability of the SEP source, the geometry of the magnetic connection between the SEP source and the spacecraft, the fact that energetic particles can be accelerated by both the flare in the corona and the interplanetary CMEdriven shock wave, and the fact that propagation regimes different from scatter free or diffusive also exist (see, e.g., Trotta et al 2020;Prete et al 2021).…”

Section: Resultsmentioning

confidence: 99%

Reconstruction of the magnetic connection from Mercury to the solar corona during enhancements in the solar proton fluxes at Mercury

Ippolito

Plainaki

Zimbardo

et al. 2022

A&A

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Aims. We study the magnetic connection between Mercury and the solar corona based on energetic proton events measured near Mercury by MESSENGER during 2011−2013 in order to identify the possible source of the accelerated particles on the solar surface. Methods. The transport of the magnetic field lines in the heliosphere was evaluated with a Monte Carlo code that gives a random displacement at each step of the integration along the Parker magnetic field model. The simulation was tailored to each specific event by using the magnetic fluctuation levels obtained at Mercury by MESSENGER and the values of the solar wind velocity measured at 1 AU by the Advanced Composition Explorer satellite. We selected seven case studies for which an increase in the proton fluxes of at least two orders of magnitude with respect to the background level was observed. For each selected case, we took the background magnetic field map (magnetogram) at the source surface of the solar wind (r = 2.5 R⊙) into account. By considering the relative position of Mercury and the Earth on the day on which the enhancement in the proton fluxes was observed by MESSENGER, we obtained the position of the active regions on the solar surface as seen by Mercury. Results. The footpoint of the Parker spiral passing Mercury was reconstructed for all of the selected events. By considering the values of the fluctuation levels of the interplanetary magnetic field recorded by MAG-MESSENGER two days before the event and the values of the fluctuation levels of the interplanetary magnetic field on the day on which the event was observed, we are also able to appreciate the effects on the solar wind magnetic field perturbations induced by the shock of the coronal mass ejection. This technique will also be useful for the interpretation of energetic particle observations by BepiColombo.

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Section: Resultsmentioning

confidence: 99%

Reconstruction of the magnetic connection from Mercury to the solar corona during enhancements in the solar proton fluxes at Mercury

Ippolito

Plainaki

Zimbardo

et al. 2022

A&A

Self Cite

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“…On the other hand, many physical systems exhibit anomalous transport, meaning that the mean square displacement grows nonlinearly in time, i.e., ∆x 2 ∝ t γ , with γ < 1 for subdiffusion and γ > 1 for superdiffusion [1][2][3][4]. In astrophysics and space physics there are several indications of superdiffusive transport of energetic particles, which come from the observations of nonrelativistic solar electrons [5], from the analysis of energetic particle profiles observed by spacecraft at shock crossings [6][7][8][9][10], from the analysis of electron transport at the Coma cluster of galaxies [11], from the analysis of the extended precursor of supernova remnants [12,13], and from the radio-derived energy spectra of galaxy cluster merger shocks [14,15]. Furthermore, we notice that many observations of solar energetic particles are consistent with very weak pitch-angle scattering and long (even larger than one astronomical unit) mean free paths, so that "scatter free" propagation is also stemming out from measurements.…”

Section: Introductionmentioning

confidence: 99%

Energetic Particle Superdiffusion in Solar System Plasmas: Which Fractional Transport Equation?

2021

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Superdiffusive transport of energetic particles in the solar system and in other plasma environments is often inferred; while this can be described in terms of Lévy walks, a corresponding transport differential equation still calls for investigation. Here, we propose that superdiffusive transport can be described by means of a transport equation for pitch-angle scattering where the time derivative is fractional rather than integer. We show that this simply leads to superdiffusion in the direction parallel to the magnetic field, and we discuss some advantages with respect to approaches based on transport equations with symmetric spatial fractional derivates.

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Energetic particle fluxes at heliospheric shocks: Evidences of superdiffusion and comparison between analytical and numerical modeling

Cited by 2 publications

References 50 publications

Reconstruction of the magnetic connection from Mercury to the solar corona during enhancements in the solar proton fluxes at Mercury

Reconstruction of the magnetic connection from Mercury to the solar corona during enhancements in the solar proton fluxes at Mercury

Energetic Particle Superdiffusion in Solar System Plasmas: Which Fractional Transport Equation?

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