A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
A Detailed Survey of the Parallel Mean Free Path of Solar Energetic Particle Protons and Electrons
Tekijät: Lang, J. T.; Strauss, R. D.; Engelbrecht, N. E.; van den Berg, J. P.; Dresing, N.; Ruffolo, D.; Bandyopadhyay, R.
Kustantaja: IOP Publishing Ltd
Kustannuspaikka: BRISTOL
Julkaisuvuosi: 2024
Journal: Astrophysical Journal
Tietokannassa oleva lehden nimi: ASTROPHYSICAL JOURNAL
Lehden akronyymi: ASTROPHYS J
Artikkelin numero: 105
Vuosikerta: 971
Numero: 1
Sivujen määrä: 15
ISSN: 0004-637X
eISSN: 1538-4357
DOI: https://doi.org/10.3847/1538-4357/ad55c3
Verkko-osoite: https://iopscience.iop.org/article/10.3847/1538-4357/ad55c3
Rinnakkaistallenteen osoite: https://research.utu.fi/converis/portal/detail/Publication/457650707
In this work, more than a dozen solar energetic particle (SEP) events are identified where the source region is magnetically well connected to at least one spacecraft at 1 au. The observed intensity-time profiles, for all available proton and electron energy channels, are compared to results computed using a numerical one-dimensional SEP transport model in order to derive the parallel mean free paths (pMFPs) as a function of energy (or rigidity) at 1 au. These inversion results are then compared to theoretical estimates of the pMFP, using observed turbulence quantities with observationally motivated variations as input. For protons, a very good comparison between inversion and theoretical results is obtained. It is shown that the observed inter-event variations in the inversion pMFP values can be explained by natural variations in the background turbulence values. For electrons, there is relatively good agreement with pMFPs derived assuming the damping model of dynamical turbulence, although the theoretical values are extremely sensitive to the details of the turbulence dissipation range, which themselves display a high level of variation.
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This work is based on the research supported in part by the National Research Foundation of South Africa (NRF grant Nos. RA170929263913, SRUG220322419, 142149, and 137793). Opinions expressed and conclusions arrived at are those of the authors and are not necessarily to be attributed to the NRF. The responsibility of the contents of this work is with the authors. J.T.L. acknowledges partial financial support from the South African National Astrophysics and Space Science Program (NASSP) and the North-West University (NWU). Figures were prepared with Matplotlib (Hunter 2007) and certain calculations were done with NumPy (Harris et al. 2020). N.D. acknowledges the support of the Academy of Finland (SHOCKSEE, grant No. 346902). D.R. acknowledges financial support from the National Science and Technology Development Agency (NSTDA) and National Research Council of Thailand (NRCT): High-Potential Research Team Grant Program (N42A650868) and from the NSRF via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation (B39G670013). The SERPENTINE project was funded by the European Union's Horizon 2020 framework program.
