Multi-messenger emission derived from relativistic magnetized jet dynamics using a multi-zone framework

TL;DR

This study couples 3D relativistic MHD simulations with a multi-zone lepto-hadronic model to explore the origins of high-energy neutrinos from AGN jets, highlighting the importance of particle acceleration mechanisms.

Contribution

It introduces a novel multi-zone framework integrating jet dynamics with lepto-hadronic modeling to better understand neutrino production in AGN jets.

Findings

Flat proton energy spectra (index ~2.0) are needed for significant neutrino flux.

Intrinsic shocks may not produce sufficiently flat particle distributions.

Alternative particle acceleration pathways are required for high neutrino emission.

Abstract

Relativistic jets from Active Galactic Nuclei (AGN) are highly energetic and emit radiation across a wide range of frequencies. Despite several observational studies, their particle composition still remains a key open question. The detection of high-energy neutrinos from blazar sources such as TXS 0506+056 has highlighted the plausibility of hadronic/lepto-hadronic models for AGN jets. To understand the origin of high-energy neutrinos from such sources, it is imperative to capture the complex interplay between the jet dynamics, their composition, and the mechanism of particle acceleration and cooling in relativistic jets. In this pilot study, we have coupled a numerical multi-zone framework for lepto-hadronic modeling, with 3D relativistic magneto-hydrodynamic simulations of AGN jets, including external photon fields. Our framework provides synthetic multi-wavelength and neutrino flux by spatially sampling the simulated jet into multiple zones. We investigate the implications of such a framework in exploring the different intrinsic and extrinsic pathways for proton-enrichment in jets. Essentially, we find that for low proton-to-electron number density ratios, producing a substantial jet neutrino flux, requires the underlying proton energy distribution to have a relatively flat spectrum with a power-law index of $\simeq 2.0$. We further find that while intrinsic shocks triggered by kink-instabilities in the jet can accelerate electrons to high energies, they may not be sufficient to produce such flat particle energy distributions for the chosen set of parsec-scale jet parameters. Finally, to produce a significant jet neutrino emission, our simulations suggest the need to consider particle acceleration mechanisms through alternative pathways, either internal or external.