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This study proposes that the observed spectral break at approximately 30 TeV in the diffuse neutrino background detected by IceCube can be explained by the activity cycles of active galactic nuclei (AGNs). The researchers developed a model linking active and quiescent phases of AGNs, where cosmic rays accelerated during active periods undergo diffusion and hadronic interactions in the host galaxy during quiet periods, producing a characteristic dual spectral break pattern. The model successfully accounts for both the IceCube diffuse neutrino flux and neutrino emissions from specific sources including blazars and Seyfert galaxies.
Why it matters
This work addresses a fundamental puzzle in multi-messenger astrophysics by providing a unified explanation for the diffuse neutrino background and its spectral features. The findings suggest that understanding temporal variability in AGN activity is crucial for tracing the origins of high-energy cosmic rays and neutrinos, which has implications for identifying the most energetic particle accelerators in the universe.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: The physical origin of the diffuse neutrino background and its spectral break at $sim$ 30 TeV remain a major puzzle in multi-messenger astrophysics. In this work, we demonstrate that this spectral feature is a natural consequence of AGN activity cycles and the resulting cosmic ray (CR) propagation. We present a unified model coupling the active and quiescent phases of AGNs, where CRs accelerated in the active core undergo subsequent diffusion and hadronic interactions in the host galaxy during the quiescent phase. The superposition of these distinct evolutionary phases yields dual spectral breaks, particularly the one at tens of TeV. Under realistic energetics, our model simultaneously accounts for the IceCube diffuse flux and fits the neutrino emissions of diverse sources, ranging from the blazar TXS 0506+056 to the Seyfert galaxies NGC 7469, CGCG 420-015, and the Circinus Galaxy. Our findings reveal that temporal variability is essential for deciphering the cosmic neutrino landscape and tracking high-energy CR escape.
Source: Deciphering the IceCube Diffuse Neutrino Observations via AGN Variability