eprintid: 10191587 rev_number: 6 eprint_status: archive userid: 699 dir: disk0/10/19/15/87 datestamp: 2024-05-03 08:25:34 lastmod: 2024-05-03 08:25:34 status_changed: 2024-05-03 08:25:34 type: article metadata_visibility: show sword_depositor: 699 creators_name: Zaslavsky, Arnaud creators_name: Kasper, Justin C creators_name: Kontar, Eduard P creators_name: Larson, Davin E creators_name: Maksimovic, Milan creators_name: Marques, José MDC creators_name: Nicolaou, Georgios creators_name: Owen, Christopher J creators_name: Romeo, Orlando creators_name: Whittlesey, Phyllis L title: Probing Turbulent Scattering Effects on Suprathermal Electrons in the Solar Wind: Modeling, Observations, and Implications ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F63 note: Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. abstract: This study explores the impact of a turbulent scattering mechanism, akin to those influencing solar and galactic cosmic rays propagating in the interplanetary medium, on the population of suprathermal electrons in the solar wind. We employ a Fokker–Planck equation to model the radial evolution of electron pitch angle distributions under the action of magnetic focusing, which moves the electrons away from isotropy, and of a diffusion process that tends to bring them back to it. We compare the steady-state solutions of this Fokker–Planck equation with data obtained from the Solar Orbiter and Parker Solar Probe missions and find a remarkable agreement, varying the turbulent mean free path as the sole free parameter in our model. The obtained mean free paths are of the order of the astronomical unit, and display weak dependence on electron energy within the 100 eV–1 keV range. This value is notably lower than Coulomb collision estimates but aligns well with observed mean free paths of low-rigidity solar energetic particle events. The strong agreement between our model and observations leads us to conclude that the hypothesis of turbulent scattering at work on electrons at all heliospheric distances is justified. We discuss several implications, notably the existence of a low Knudsen number region at large distances from the Sun, which offers a natural explanation for the presence of an isotropic “halo” component at all distances from the Sun—electrons being isotropized in this distant region before traveling back into the inner part of the interplanetary medium. date: 2024-05-01 date_type: published publisher: American Astronomical Society official_url: http://dx.doi.org/10.3847/1538-4357/ad2e92 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2271975 doi: 10.3847/1538-4357/ad2e92 lyricists_name: Nicolaou, Georgios lyricists_name: Owen, Christopher lyricists_id: GNICO14 lyricists_id: CJOWE13 actors_name: Flynn, Bernadette actors_id: BFFLY94 actors_role: owner full_text_status: public publication: The Astrophysical Journal volume: 966 number: 1 article_number: 60 issn: 0004-637X citation: Zaslavsky, Arnaud; Kasper, Justin C; Kontar, Eduard P; Larson, Davin E; Maksimovic, Milan; Marques, José MDC; Nicolaou, Georgios; ... Whittlesey, Phyllis L; + view all <#> Zaslavsky, Arnaud; Kasper, Justin C; Kontar, Eduard P; Larson, Davin E; Maksimovic, Milan; Marques, José MDC; Nicolaou, Georgios; Owen, Christopher J; Romeo, Orlando; Whittlesey, Phyllis L; - view fewer <#> (2024) Probing Turbulent Scattering Effects on Suprathermal Electrons in the Solar Wind: Modeling, Observations, and Implications. The Astrophysical Journal , 966 (1) , Article 60. 10.3847/1538-4357/ad2e92 <https://doi.org/10.3847/1538-4357%2Fad2e92>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10191587/1/Zaslavsky_2024_ApJ_966_60.pdf