The modulation of anomalous and galactic cosmic ray oxygen over successive solar cycle minima

Abstract

Both the recent 2009 and 2020 solar minima were classified as unusually quiet and characterized with unusually high galactic cosmic ray (GCR) levels. However, unlike the trends from previous decades in which anomalous cosmic ray (ACR) and GCR levels strongly agreed, the ACR intensities did not reach such high record-setting levels.This discrepancy between the behaviour of GCRs and ACRs is investigated in this work by simulating the acceleration and transport of GCR and ACR oxygen under different transport conditions. After using recent observations to constrain any remaining free parameters present in the model, we show that less turbulent conditions are characterized by higher GCR fluxes and low ACR fluxes due to less efficient ACR acceleration at the solar wind termination shock. We offer this as an explanation for the ACR/GCR discrepancy observed during 2009 and 2020, when compared to previous solar cycles.

arXiv commentAccepted to ApJ

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• Array Programming with NumPy
• New very local interstellar spectra for electrons, positrons, protons and light cosmic ray nuclei
• Deciphering the local Interstellar spectra of primary cosmic ray species with HelMod
• Variations of the Galactic Cosmic Rays in the Recent Solar Cycles
• Anomalous Cosmic Ray Oxygen Observations in to 0.1 au
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Cited by in corpus (1)

• Anomalous cosmic rays within the inner heliosphere: Observations of helium by the High Energy Telescope onboard Solar Orbiter