A Study of Plasma Jets Formed by Astrophysical Shocks and an Investigation of the Relationship between Instabilities and Jet Propagation

Abstract

     Scientists are investigating the astrophysical shock phenomena responsible for the origins of plasma jets while also working to determine the relationships between these jets and the instabilities they produce. Galactic energy jets emitted from active galactic nuclei provide energy that reshapes our understanding of galaxy evolution, influencing how gas clusters cool and how supermassive black holes transform. Through extensive research and online resources, scientists have demonstrated the fundamental processes involved in jet-surrounding medium interactions and have clarified the structural dynamics of plasma jets. However, the initial cause of the Fanaroff–Riley (FR) morphological division, distinguishing between (FRII and FRI) jet types based on size and structure, remains unknown. Gaining this understanding requires conducting global three-dimensional magnetohydrodynamic simulations of jet acceleration in matter. Jets experience delayed propagation and compression as they travel through galactic nuclei with flat density profiles, which increases the likelihood of three-dimensional magnetic curvature instabilities. This study identifies a key factor influencing jet behavior: the core’s mass and radius. Under certain conditions, “leaky” behavior appears in the core, where jets stall before expanding as cavity-forming plasma regions. Once the critical force threshold is exceeded, the jets escape the core, producing strong reverse flows. The morphological features of jets and the observed (FR) dichotomy can be explained by curvature instability mechanisms. Moreover, the values of the critical forces correspond well with previous measurements of galaxy optical brightness.

To explore, we run global three-dimensional magnetohydrodynamic computations of accelerated jets moving through a material. Our findings show that galactic nuclei's flat density profiles delay and compress jets, rendering them prone to three-dimensional magnetic curvature instabilities. We discover a crucial factor that, depending on the mass and radius of the galactic core, causes jets to become Leaky inside the core, stall, and expand into cavities filled with moderately hot plasma. When this critical force is surpassed, the jets can exit the core, resulting in powerful reverse jets. Thus, curvature instability plays an important role in jet morphology and might explain the FR dichotomies. Furthermore, the projected link between the critical force and a galaxy's optical brightness is consistent with previous measurements.