The anatomy of a star-forming galaxy: Pressure-driven regulation of star formation in simulated galaxies

TL;DR

This paper investigates how pressure-driven feedback mechanisms regulate star formation in simulated galaxies, emphasizing the importance of vertical ISM structure and developing a model that accurately predicts star formation responses.

Contribution

It introduces a pressure-driven regulation framework that explains the sub-linear star formation dependence and highlights the significance of vertical ISM resolution in simulations.

Findings

Star formation scales sub-linearly with feedback parameters.

Vertical ISM structure resolution impacts star formation regulation.

A simple pressure-driven model accurately predicts star formation response.

Abstract

We explore the regulation of star formation in star-forming galaxies through a suite of high-resolution isolated galaxy simulations. We use the SPH code GASOLINE, including photoelectric heating and metal cooling, which produces a multi-phase interstellar medium. We show that representative star formation and feedback sub-grid models naturally lead to a weak, sub-linear dependence between the amount of star formation and changes to star formation parameters. We incorporate these sub-grid models into an equilibrium pressure-driven regulation framework. We show that the sub-linear scaling arises as a consequence of the non-linear relationship between scale height and the effective pressure generated by stellar feedback. Thus, simulated star-formation regulation is sensitive to how well vertical structure in the ISM is resolved. Full galaxy disks experience density waves which drive locally time-dependent star formation. We develop a simple time-dependent, pressure-driven model that reproduces the response extremely well.