MHD Effects on Pulsed YSO Jets. I. 2.5-D Simulations

TL;DR

This study uses high-resolution 2.5-D MHD simulations with microphysics to analyze the dynamics and emission features of pulsed radiative jets from young stellar objects, highlighting the role of magnetic pinch forces.

Contribution

It introduces detailed 2.5-D MHD simulations with microphysics to examine jet dynamics and emission, emphasizing magnetic pinch effects within pulsed jets.

Findings

Pinch forces enhance axial emission regions in stronger magnetic fields.

Simulations reveal complex shock and rarefaction structures due to pulsed ejection velocities.

Magnetic effects influence the emission morphology of jets.

Abstract

In this paper we explore the dynamics of radiative axisymmetric MHD jets at high resolution using AMR methods. The goal of the study is to determine both the dynamics and emission properties of such jets. To that end we have implemented microphysics enabling us to produce synthetic maps of H$\alpha$ and [S II]. The jets are pulsed either sinusoidally or randomly via a time-dependent ejection velocity which leads to a complicated structure of internal shocks and rarefactions as has been seen in previous simulations. The high resolution of our simulations allows us to explore in great detail the effect of pinch forces (due to the jet's toroidal magnetic field) within the "working surfaces" where pulses interact. We map the strong H$\alpha$ emission marking shock fronts and the strong [S II] emission inside cooling regions behind shocks as observed with high-resolution images of jets. We find that pinch forces in the stronger field cases produce additional emission regions along the axis as compared with purely hydrodynamic runs. These simulations are a first step to understanding the full 3-D emission properties of radiative MHD jets.