Speaker
Description
Stochastic particle acceleration in magnetized turbulent plasmas, and its resulting multi-messenger signatures, has received increased attention in recent years. A detailed modeling of this process is however made complex by the need to treat simultaneously particle acceleration and radiative processes.
We present here a hybrid numerical code that couples AM3 [1], a state-of-the-art, open-source, time-dependent lepto-hadronic radiative modeling tool, with a particle acceleration solver based on a momentum-space transport equation. The acceleration module incorporates recent theoretical developments, in particular the non-linear feedback of accelerated particles on the turbulent cascade [2] and a generalized transport equation in momentum space to model particle acceleration in strong turbulence [3]. This new framework therefore enables a self-consistent modeling of particle acceleration and the associated multi-wavelength and multi-messenger emission, making it a powerful tool to study turbulence-driven acceleration and to produce predictive signatures for comparison with observations.
Recent observations by the Ice Cube collaboration of multi-TeV neutrinos associated with nearby Seyfert galaxies provide specific motivation for this tool [4]. The inferred neutrino flux is at least an order of magnitude larger than the photon flux at similar energies, indicating that neutrinos originate from a region opaque to γ-ray photons. A natural candidate for such an environment is the accreting corona surrounding the central supermassive black hole, where photo-hadronic interactions can occur between the intense radiation field and protons stochastically accelerated by turbulence [5].
Using the hybrid code, we model the coronal plasma including stochastic proton acceleration, feedback on the turbulent spectrum, interactions with the local photon field, and the flow dynamics. The model successfully reproduces the IceCube neutrino flux within a physically motivated corona scenario. This provides a self-consistent explanation for the neutrino emission from NGC 1068 and offers a general framework for studying turbulence-driven particle acceleration and multi-messenger signatures in other astrophysical sources.
[1] M. Klinger et al.: AM3: An open-source tool for time-dependent lepto-hadronic modeling of astrophysical sources, Astrophys.J.Supp. 275 (2024) 1, 4
[2] M. Lemoine, K. Murase, F. Rieger: Nonlinear aspects of stochastic particle acceleration, Phys. Rev. D109, 063006 (2024)
[3] M. Lemoine: First-Principles Fermi Acceleration in Magnetized Turbulence, Phys. Rev. Lett. 129, 215101 (2022)
[4] IceCube Collaboration: Evidence for neutrino emission from the nearby active galaxy NGC 1068, Science 378, 6619, 538-543 (2022)
[5] A. Das, T. Zhang, K. Murase: Revealing the Production Mechanism of High-Energy Neutrinos from NGC 1068, Astrophys.J. 972 (2024) 44
