Density PDFs of diffuse gas in the Milky Way

TL;DR

This paper demonstrates that the density PDFs of diffuse ionized and atomic gas in the Milky Way are lognormal, supporting the idea that turbulence shapes the density structure of the interstellar medium.

Contribution

It provides observational evidence that the density PDFs of diffuse gas are lognormal, reinforcing turbulence-based models of the ISM structure.

Findings

Density PDFs are close to lognormal for both DIG and atomic gas.

Line of sight inclination affects the PDF shape.

Supports turbulent origin of ISM density structure.

Abstract

The probability distribution functions (PDFs) of the average densities of the diffuse ionized gas (DIG) and the diffuse atomic gas are close to lognormal, especially when lines of sight at |b|<5 degree and |b|>5 degree are considered separately. Our results provide strong support for the existence of a lognormal density PDF in the diffuse ISM, consistent with a turbulent origin of density structure in the diffuse gas.