Photoionized gas in hydrostatic equilibrium: the role of gravity

TL;DR

This paper introduces a method to incorporate gravity into plasma modeling with Cloudy, demonstrating its impact on the structure and composition of galactic gas disks, with implications for astrophysical simulations.

Contribution

A novel approach to include gravity in plasma physics simulations, enabling more accurate modeling of hydrostatic equilibrium in astrophysical environments.

Findings

Gravity influences the scale height of galactic disks.

Gravitational effects significantly affect chemical composition predictions.

Magnetic fields and radiation shape the disk structure.

Abstract

We present a method to include the effects of gravity in the plasma physics code Cloudy. More precisely, a term is added to the desired gas pressure in order to enforce hydrostatic equilibrium, accounting for both the self-gravity of the gas and the presence of an optional external potential. As a test case, a plane-parallel model of the vertical structure of the Milky Way disk near the solar neighbourhood is considered. It is shown that the gravitational force determines the scale height of the disk, and it plays a critical role in setting its overall chemical composition. However, other variables, such as the shape of incident continuum and the intensity of the Galactic magnetic field, strongly affect the predicted structure.