Energy Deposition By Galactic Cosmic Rays And Implications For Ozone Chemistry

We present a Monte Carlo study of galactic cosmic-ray (GCR) energy deposition and its implications for stratospheric chemistry, performed with the Geant4 toolkit.

Primary nuclei (protons, α, CNO, and Si) were propagated through an atmosphere modeled from 0 to 120~g~cm⁻², considering both Polar (R_c=0.1~GV) and Equatorial (R_c=15~GV) geomagnetic cutoff conditions. The simulations resolve the variation of energy deposition with altitude for primary and secondary particles, revealing that ∼~96% of the stratospheric energy budget arises from cascade secondaries within the 15–35~km domain.

By converting layer-resolved energy deposition into ion pair production rates, we quantify the resulting formation of odd nitrogen (NO_x) and odd hydrogen (HO_x) radicals, which catalyze the destruction of ozone.

The modeled production rates peak between 18 and 22~km altitude, leading to an estimated fractional ozone decrease of order 10⁻³–10⁻² under average GCR fluxes, consistent with observed background modulation over the solar cycle. These results establish a physically consistent link between cosmic-ray induced energy deposition and ozone chemistry, providing a benchmark framework for coupling high-energy particle transport to atmospheric photochemical models.

Luiz Augusto Stuani Pereia, Rita de Cássia dos Anjos

Comments: Paper accepted for publication in Physical Review D
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Cite as: arXiv:2602.22987 [astro-ph.HE] (or arXiv:2602.22987v1 [astro-ph.HE] for this version)
https://doi.org/10.48550/arXiv.2602.22987
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Submission history
From: Luiz Augusto Stuani Pereira
[v1] Thu, 26 Feb 2026 13:31:09 UTC (640 KB)
https://arxiv.org/abs/2602.22987
Astrobiology,