Jet-red giant interactions as a source of extragalactic neutrinos: Insights from KM3-230213A

TL;DR

This paper investigates the origin of a PeV neutrino event by analyzing AGN jet interactions with red giants, suggesting that different photon fields influence the neutrino energy spectrum and identifying a promising AGN candidate as the source.

Contribution

It provides a detailed physical model linking red-giant interactions in AGN jets to high-energy neutrino production, constrained by multiwavelength observations.

Findings

PMN J0606-0724 is the likely neutrino source.

Red-giant interactions drive baryon injection and shock acceleration.

Different photon fields produce neutrinos at distinct energies.

Abstract

The production sites of high-energy astrophysical neutrinos remain uncertain, though growing evidence suggests a connection to relativistic jets in active galactic nuclei (AGN). We present a detailed analysis of the recent PeV neutrino event KM3-230213A reported by the KM3NeT collaboration, aiming to constrain the physical conditions of its source. Assuming proton acceleration at shocks, we derive the properties of the proton distribution and the energetics required to explain the neutrino emission. Using contemporaneous multiwavelength observations of three AGN flaring candidates within the error region, we examine the plausibility of each of them as the possible counterpart. Our results favor PMN J0606-0724, which exhibits a prominent radio flare coincident with the neutrino arrival. In this framework, the red-giant interaction remains the key driver of baryon injection and shock acceleration, while the dominant external photon field sets the neutrino energy scale: photospheric photons from the red giant yield ~1-10 PeV neutrinos, whereas the ~220 PeV event KM3-230213A is more naturally produced through interactions with colder infrared photons from the dusty torus.