Introducing CGOLS: The Cholla Galactic OutfLow Simulation Suite

TL;DR

The CGOLS suite provides high-resolution galaxy simulations to better understand multiphase galactic winds and tests the applicability of the Chevalier & Clegg wind model, highlighting the importance of extreme resolution for accurate results.

Contribution

This work introduces the CGOLS simulation suite with unprecedented 5 pc resolution, enabling detailed study of galactic winds and testing existing wind models.

Findings

Chevalier & Clegg model fits nuclear starburst winds in non-radiative conditions

Simulations show convergence of observable features at resolutions above 10 pc

Extreme resolution is necessary to accurately model wind structures and their effects

Abstract

We present the Cholla Galactic OutfLow Simulations (CGOLS) suite, a set of extremely high resolution global simulations of isolated disk galaxies designed to clarify the nature of multiphase structure in galactic winds. Using the GPU-based code Cholla, we achieve unprecedented resolution in these simulations, modeling galaxies over a 20 kpc region at a constant resolution of 5 pc. The simulations include a feedback model designed to test the effects of different mass- and energy-loading factors on galactic outflows over kiloparsec scales. In addition to describing the simulation methodology in detail, we also present the results from an adiabatic simulation that tests the frequently-adopted analytic galactic wind model of Chevalier & Clegg. Our results indicate that the Chevalier & Clegg model is a good fit to nuclear starburst winds in the non-radiative region of parameter space. Lastly, we investigate the role of resolution and convergence in large-scale simulations of multiphase galactic winds. While our largest-scale simulations do show convergence of observable features like soft X-ray emission, our tests demonstrate that simulations of this kind with resolutions greater than 10 pc are not yet converged, confirming the need for extreme resolution in order to study the structure of winds and their effects on the circumgalactic medium.