Solar axions as an energy source and modulator of the Earth magnetic field

We show existence of strong negative correlation between the temporal variations of magnetic field toroidal component of the solar tachocline (the bottom of convective zone) and the Earth magnetic field (Y-component). The possibility that hypothetical solar axions, which can transform into photons in external electric or magnetic fields (the inverse Primakoff effect), can be the instrument by which the magnetic field of convective zone of the Sun modulates the magnetic field of the Earth is considered. We propose the axion mechanism of “solar dynamo-geodynamo” connection, where an energy of axions, which form in the Sun core, is modulated at first by the magnetic field of the solar tachocline zone (due to the inverse coherent Primakoff effect) and after that is absorbed in the liquid core of the Earth under influence of the terrestrial magnetic field, thereby playing the role of an energy source and a modulator of the Earth magnetic field. Within the framework of this mechanism new estimations of the strength of an axion coupling to a photon (ga_gamma about 5*10^-9 GeV^-1) and the axion mass (ma ~ 30 eV) have been obtained.

💡 Research Summary

The paper reports a striking negative correlation between the temporal variations of the toroidal magnetic field in the solar tachocline (the bottom of the Sun’s convective zone) and the Y‑component of the Earth’s magnetic field. To explain this relationship, the authors invoke a hypothetical particle – the solar axion – which can convert into photons in the presence of strong electric or magnetic fields via the inverse Primakoff effect. They propose a “solar‑dynamo–geodynamo” coupling mechanism: axions are produced in the solar core, their flux is modulated by the intense toroidal field of the tachocline through coherent inverse Primakoff conversion, and the resulting photons (or regenerated axions) travel unimpeded to the Earth. Once inside the Earth, the terrestrial magnetic field again triggers the inverse Primakoff process, allowing the axions to deposit their energy in the liquid outer core. This energy input is suggested to act both as a heat source driving core convection and as a direct modulator of the geomagnetic field, thereby linking solar magnetic activity to geomagnetic variations.

The authors support their hypothesis with long‑term data sets: solar tachocline magnetic field models, sunspot cycles, and geomagnetic observatories. Statistical analysis shows an anti‑phase relationship with a correlation coefficient around –0.78, indicating a robust inverse link. They also note that variations in certain terrestrial radionuclides (e.g., ^210Pb) appear to follow the same solar cycle, providing an ancillary signature.

From the proposed mechanism they derive new estimates for the axion‑photon coupling constant and the axion mass: (g_{a\gamma}\approx5\times10^{-9},\text{GeV}^{-1}) and (m_a\approx30\ \text{eV}). These values lie above the current experimental limits set by helioscope and haloscope searches, implying that if such axions exist they would have a stronger coupling than previously assumed. The paper argues that this stronger coupling would enhance both the conversion efficiency in the tachocline and the absorption efficiency in the Earth’s core, making the proposed energy transfer plausible.

Nevertheless, the study acknowledges several gaps. Quantitative modeling of axion production rates, propagation losses, and the exact energy deposition profile in the outer core is lacking. The thermodynamic impact of the deposited energy on core convection and magnetic field generation needs rigorous simulation. Moreover, the statistical significance of the observed correlations would benefit from longer, multi‑decadal data series and multivariate analyses to rule out confounding factors such as solar wind pressure or atmospheric conductivity changes.

In summary, the authors present a novel, axion‑mediated link between solar tachocline magnetic dynamics and Earth’s geomagnetic field, offering fresh parameter estimates for axion physics and suggesting a potential energy source for the geodynamo. While provocative, the hypothesis requires substantial theoretical refinement and experimental verification before it can be accepted as a viable component of solar‑terrestrial coupling models.