Authors: F. Carcaboso (NPP NASA GSFC, HSD NASA GSFC), D. Lario (HSD NASA GSFC), A. Szabo (HSD NASA GSFC), J. Verniero (HSD NASA GSFC), R. Gómez-Herrero (University of Alcalá), F. Espinosa Lara (University of Alcalá)

The characterization of suprathermal electron Pitch Angle Distributions (PADs) is crucial for understanding the magnetic field topology of the solar wind and its conditions.

Various methods have been employed to extract different properties of PADs, such as strahl width or anisotropy grade. However, these methods are typically tailored for specific purposes and may not be universally applicable.

Carcaboso et al. (2020) introduced a characterization approach with broader applicability. This method involves fitting Legendre polynomials to observed suprathermal PADs and employing signal processing techniques to analyze the predominant harmonics. It offers several advantages, including automated identification of various distribution types (bidirectionality, isotropy, simple strahl, loss cone, pancake, etc.), quantification of anisotropy, and inference of strahl width.

In this study, we examine how anisotropy and electron density vary with heliocentric distance across different solar wind populations based on PSP/SWEAP/SPAN-E measurements. We also explore the behavior of various PAD types present in the solar wind.

Carcaboso, F., Gómez-Herrero, R., Lara, F. E., Hidalgo, M. A., Cernuda, I., & Rodríguez-Pacheco, J. (2020). Characterisation of suprathermal electron pitch-angle distributions-Bidirectional and isotropic periods in solar wind. Astronomy & Astrophysics, 635, A79.