Speaker
Description
Active Galactic Nuclei (AGN) and their relativistic jets have been few of the most promising astrophysical environments for particle acceleration and multi-messenger emissions. Yet the composition of these relativistic jets is still an open question in astronomy. Different models for jet composition have been proposed, starting from leptonic models to hadronic and lepto-hadronic models. The particles inside an AGN jet can be accelerated to high energies via different mechanisms, including shocks, stochastic turbulent acceleration, magnetic reconnection and entrainment driven by jet-environment interactions. Each of these mechanisms can generate distinct multi-messenger observational signatures due to the rapid changes in jet morphology and magnetic field topology. These signatures can serve as pivotal diagnostic tools to study different jet composition models.
With the detection of high-energy neutrinos from the direction of the blazar TXS 0506+056 by the IceCube Neutrino Observatory, at a significance of around 3.5 sigma, there has been renewed interest in hadronic and lepto-hadronic models of AGN jets, since unlike purely leptonic scenarios, these models produce neutrino emission. Connecting jet simulations to neutrino observations requires tools that can simultaneously evolve jet fluid dynamics and non-thermal proton microphysics. At present, there is a significant gap in the availability of such tools. While our previous work developed a numerical multi-zone framework for modeling multi-messenger emission from AGN jets, a key missing ingredient has been a dedicated treatment of proton acceleration within the jet. In this work, we address the gap by developing a new, computationally efficient proton-physics sub-module that augments the existing leptonic particle module for the fluid dynamics code called PLUTO. This sub-module evolves non-thermal protons alongside leptons for Relativistic magneto-hydrodynamic (RMHD) simulations. Coupled to our lepto-hadronic multi-zone AGN-jet framework, this enables generation of synthetic spectral energy distributions and neutrino flux predictions for diverse jet scenarios.
In this presentation, I shall introduce our newly developed proton sub-module for PLUTO code and describe our novel approach on integrating the multi-zone framework with the relativistic magneto-hydrodynamic evolution of the jet using this improved particle module. In particular, we study the effects of entrainment of proton-rich matter due to jet-environment interactions on the resulting multi-wavelength photon and neutrino emission. This framework serves as a bridge between jet dynamics and the microphysics within AGN jets, providing valuable insights on how the complex interplay between the jet dynamics, particle acceleration mechanisms and jet composition effects the subsequent multi-messenger emissions from AGN jet.