Long-term FRII jet evolution: Clues from three-dimensional simulations

TL;DR

This paper presents comprehensive 3D simulations of relativistic FRII jets, revealing faster propagation, the impact of helical instabilities, and significant feedback effects on galactic environments, aligning well with observations.

Contribution

The study provides the first long-term 3D simulation of relativistic jets from 1 to 200 kpc, highlighting differences from 2D models and emphasizing the role of instabilities and feedback.

Findings

Jet propagation is faster than 2D predictions.

Helical instabilities slow down jet head movement.

Shock heating significantly influences galactic feedback.

Abstract

We present a long-term numerical three-dimensional simulation of a relativistic outflow designed to be compared with previous results from axisymmetric, two-dimensional simulations, with existing analytical models and state-of-art observations. We follow the jet evolution from 1~kpc to 200~kpc, using a relativistic gas equation of state and a galactic profile for the ambient medium. We also show results from smaller scale simulations aimed to test convergence and different three-dimensional effects. We conclude that jet propagation can be faster than expected from axisymmetric simulations, covering tens of kiloparsecs in a few million years, until the dentist drill effect produced by the growth of helical instabilities slows down the propagation speed of the jet head. A comparison of key physical parameters of the jet structure as obtained from the simulations with values derived from observations of FRII sources reveals good agreement. Our simulations show that shock heating can play a significant role in the feedback from active galaxies, confirming previous 2D results. A proper description of galactic jets as a relativistic scenario, both dynamical and thermodynamical, reveals an extremely fast and efficient feedback process reheating the ICM, and therefore, with dramatic consequences on the galactic evolution. Our results point towards FRII jets as the source of the energetic electrons observed in radio relics.