Can the neutrinos from TXS 0506+056 have a coronal origin?

TL;DR

This paper investigates whether the high-energy neutrinos from blazar TXS 0506+056 originate from its core region or the jet, concluding that the jet is the more likely source based on coronal emission estimates.

Contribution

The study evaluates the coronal origin hypothesis for neutrinos in TXS 0506+056 and demonstrates that coronal neutrino emission is insufficient to explain observations, favoring jet-based production.

Findings

Coronal neutrino emission is too low to account for IceCube observations.

Magnetic reconnection is essential for accelerating protons to tens of PeV.

Jet-based processes remain the preferred explanation for neutrino production.

Abstract

The blazar TXS 0506+056 has been the first astrophysical source associated with high-energy astrophysical neutrinos, and it has emerged as the second-most-prominent hotspot in the neutrino sky over ten years of observations. Although neutrino production in blazars has traditionally been attributed to processes in the powerful relativistic jet, the observation of a significant neutrino flux from NGC 1068 -- presumably coming from the Active Galactic Nucleus (AGN) corona -- suggests that neutrinos can also be produced in the cores of AGN. This raises the question whether neutrino production in TXS~0506+056 is also associated with the core region. We study this scenario, focusing on the hypothesis that this blazar is a masquerading BL Lac, a high-excitation quasar with hidden broad emission lines and a standard accretion disk. We show that magnetic reconnection is an acceleration process necessary to reach tens of PeV proton energies, and we use observationally motivated estimates of the X-ray luminosity of the coronal region to predict the emission of secondaries and compare them to the observed multi-wavelength and neutrino spectra of the source. We find that the coronal neutrino emission from TXS 0506+056 is too low to describe the IceCube observed neutrinos from this AGN, which in turn suggests that the blazar jet remains the preferred location for neutrino production.