On the consistency of jet feedback modelling across different astrophysics hydrodynamical codes

TL;DR

This study compares how different hydrodynamical simulation codes model AGN jet feedback, revealing that solver differences influence jet morphology but have limited impact on overall galaxy evolution predictions.

Contribution

Introduces a new subgrid jet-launching method implemented across multiple hydrodynamical codes to assess solver-dependent differences in jet evolution.

Findings

Jet morphology varies significantly between codes.

Despite morphological differences, the impact on ambient medium is similar.

Solver differences are likely subdominant to subgrid model uncertainties.

Abstract

Active Galactic Nuclei (AGN) feedback is essential in cosmological simulations of galaxy formation, yet its implementation has to rely on subgrid models due to limited resolution. We present a novel subgrid jet-launching method for galaxy formation simulations and implement it in three hydrodynamical codes: the smoothed particle hydrodynamics (SPH) code SWIFT, the moving-mesh code AREPO, and the Eulerian grid code PLUTO. To isolate the impact of hydrodynamical solvers on jet evolution, we compare idealised jets and their remnants in uniform and stratified media across resolutions and jet parameters. In uniform media, all jets drive bow shocks, inflate hot lobes, exhibit backflows, and evolve self-similarly. For the parameters explored, SWIFT lobes are shorter, wider, and hotter; AREPO lobes are longer, thinner, and cooler; while PLUTO lobes display complex flows with intermediate characteristics. In stratified media, jets deviate from self-similar evolution, inflating longer and thinner lobes due to lower external ram pressure. After switch-off, SWIFT jets evolve into smooth cylindrical bubbles, AREPO jets produce long filamentary remnants, and PLUTO jets yield intermediate-length remnants with varying degrees of mixing. Despite such differences, all jets and remnants have a similar impact on the ambient medium. We conclude that variations in lobe properties between codes emerge even for identical subgrid prescriptions, since the coupling of jet feedback to resolvable scales and the effective resolution depend on the hydrodynamical method. In structure formation simulations, these solver differences are likely subdominant to uncertainties in subgrid modelling and calibration, while averaging over galaxy populations may lessen their impact.