Quantifying the anisotropic density structure of the Central Molecular Zone -- a 2D correlation function approach

TL;DR

This study uses a 2D correlation function approach to quantify the anisotropic density structure of the Central Molecular Zone in the Milky Way, revealing scale-dependent anisotropy in gas distribution.

Contribution

It introduces a formalism to measure and analyze the anisotropic density structure of the CMZ using 870 μm continuum data, providing a quantitative description of spatial anisotropy.

Findings

Density structure is strongly anisotropic at ~100 pc scale

Anisotropy decreases at smaller scales (~10 pc)

The formalism can be applied to other regions for comparison

Abstract

The Central Molecular Zone (CMZ) is a ring-like structure sitting at the center of the Milky Way. Using the 870 $\mu$m continuum map from the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL), we study the anisotropy of the density structure of the gas in the Central Molecular Zone (CMZ) using the 2D correlation function. To quantify the spatial anisotropy, we define the critical angle $\theta_{\rm half}$, as well as the anisotropy parameter $A\equiv \frac{\pi}{4\theta_{\rm half}}-1$. We find that the density structure is strongly anisotropic at the large scale (~ 100 pc), and the degree of spatial anisotropy decreases with the decreasing scale. At the scale of ~ 10 pc, the structure is still mildly anisotropic. In our analyses, we provide a quantitative description of the anisotropic density structure of gas in the CMZ, and the formalism can be applied to different regions to study their differences.