Solving the multi-messenger puzzle of the AGN-starburst composite galaxy NGC 1068

TL;DR

This paper develops a two-zone multi-messenger model to explain the high-energy emission from the AGN-starburst galaxy NGC 1068, successfully fitting data from radio to neutrinos and highlighting the importance of considering both regions.

Contribution

It introduces a homogeneous, steady-state two-zone model for non-thermal emission in AGN-starburst galaxies, applied specifically to NGC 1068, demonstrating the necessity of both regions for accurate data representation.

Findings

The combined model fits the entire multi-messenger spectrum of NGC 1068.

Single-region models are insufficient to explain the observed data.

The model accounts for neutrino emission constraints.

Abstract

Multi-wavelength observations indicate that some starburst galaxies show a dominant non-thermal contribution from their central region. These active galactic nuclei (AGN)-starburst composites are of special interest, as both phenomena on their own are potential sources of highly-energetic cosmic rays and associated gamma-ray and neutrino emission. In this work, a homogeneous, steady-state two-zone multi-messenger model of the non-thermal emission from the AGN corona as well as the circumnuclear starburst region is developed and subsequently applied to the case of NGC 1068, which has recently shown some first indications of high-energy neutrino emission. Here, we show that the entire spectrum of multi-messenger data - from radio to gamma-rays including the neutrino constraint - can be described very well if both, starburst and AGN corona, are taken into account. Using only a single emission region is not sufficient.