The Effects of Resolution on Black Hole Accretion Simulations of Jets

TL;DR

This study investigates how grid resolution affects the accuracy of black hole jet simulations, finding that many key results are consistent across different resolutions, supporting the reliability of coarser grid models.

Contribution

The paper provides a systematic analysis of the impact of grid resolution on general-relativistic magnetohydrodynamic simulations of black hole jets, demonstrating the robustness of most results.

Findings

Jet power and structure are consistent across resolutions.

Some variability and magnetization measures are resolution-sensitive.

Coarser grids yield reliable results for many jet properties.

Abstract

We perform three general-relativistic magnetohydrodynamic simulations of black hole accretion designed to test how sensitive results are to grid resolution in the jet region. The cases differ only in numerics, modelling the same physical scenario of a radiatively inefficient, geometrically thick, magnetically arrested flow onto a rapidly spinning black hole. Properties inferred with the coarsest grid generally agree with those found with higher resolutions, including total jet power and its decomposition into different forms, velocity structure, nonaxisymmetric structure, and the appearance of resolved millimetre images. Some measures of variability and magnetization are sensitive to resolution. We conclude that most results obtained by limiting resolution near the jet for computational expediency should still be reliable, at least insofar as they would not be improved with a finer grid.