Dynamical and radiative properties of astrophysical supersonic jets I. Cocoon morphologies

TL;DR

This paper presents a numerical study of how supersonic astrophysical jets propagate and interact with their environment, focusing on cocoon morphology and the influence of jet head velocity on lobe structures.

Contribution

It introduces a numerical scheme that models jet propagation in a moving reference frame, enabling detailed analysis of cocoon shapes under various physical conditions.

Findings

Jet head velocity significantly affects cocoon morphology.

Morphological features relate to the origin of radio lobes.

Simulation results match observed lobe structures.

Abstract

We present the results of a numerical analysis of the propagation and interaction of a supersonic jet with the external medium. We discuss the motion of the head of the jet into the ambient in different physical conditions, carrying out calculations with different Mach numbers and density ratios of the jet to the exteriors. Performing the calculation in a reference frame in motion with the jet head, we can follow in detail its long term dynamics. This numerical scheme allows us also to study the morphology of the cocoon for different physical parameters. We find that the propagation velocity of the jet head into the ambient medium strongly influences the morphology of the cocoon, and this result can be relevant in connection to the origin and structure of lobes in extragalactic radiosources.