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arXiv · 2512.24178

A Seyfert galaxy as a hidden counterpart to a neutrino-associated blazar

Emma Kun·Santiago del Palacio·Imre Bartos·Francis Halzen·Julia Becker Tjus·Peter L. Biermann·Anna Franckowiak·Claudio Ricci
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Abstract

The origin and production mechanisms of high-energy astrophysical neutrinos remain open questions in multimessenger astronomy. Previous studies have hinted at a possible linear correlation between the hard X-ray and high-energy neutrino emission in active galactic nuclei. New \textit{NuSTAR} observations, first presented here, reveal that blazar PKS 1424+240, located within a prominent IceCube neutrino hotspot, is far fainter in hard X-rays than expected from this trend. Motivated by this apparent ambiguity, we identify the nearby Seyfert galaxy NGC 5610, also coincident with the hotspot, whose unabsorbed hard X-ray flux exceeds that of PKS 1424+240 by about an order of magnitude. When the local IceCube neutrino flux is apportioned between the two AGN in proportion to their hard X-ray emission, both align with the previously suggested X-ray-neutrino correlation. This suggests that certain IceCube hotspots may be unresolved blends of multiple AGN, and supports a multimessenger scenario in which high-energy neutrinos and hard X-rays originate from the same hadronic interactions, with the X-ray emission produced through cascade reprocessing.

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Emma Kun, Santiago del Palacio, Imre Bartos, Francis Halzen, Julia Becker Tjus, Peter L. Biermann, Anna Franckowiak, Claudio Ricci. 2025-12-30. A Seyfert galaxy as a hidden counterpart to a neutrino-associated blazar. https://arxiv.org/abs/2512.24178

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