Towards a three-dimensional distribution of the molecular clouds in the Galactic Centre

Abstract

We present a study of the three-dimensional structure of the molecular clouds in the Galactic Centre (GC) using CO emission and OH absorption lines. Two CO isotopologue lines, ${}^{12}$CO ($J$=1$\to$0) and ${}^{13}$CO ($J$=1$\to$0), and four OH ground-state transitions, surveyed by the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH), contribute to this study. We develop a novel method to calculate the OH column density, excitation temperature, and optical depth precisely using all four OH lines, and we employ it to derive a three-dimensional model for the distribution of molecular clouds in the GC for six slices in Galactic latitude. The angular resolution of the data is 15.5 arcmin, which at the distance of the GC (8.34 kpc) is equivalent to 38 pc. We find that the total mass of OH in the GC is in the range 2400-5100 Solar mass . The face-on view at a Galactic latitude of b = 0° displays a bar-like structure with an inclination angle of 67.5 $\pm$ 2.1° with respect to the line of sight. No ring-like structure in the GC is evident in our data, likely due to the low spatial resolution of the CO and OH maps.

Accepted for publication in MNRAS, 15 pages, 12 figures

References in corpus (8)

• The Structure of the Milky Way's Bar Outside the Bulge
• The dynamical evolution of molecular clouds near the Galactic Centre - I. Orbital structure and evolutionary timeline
• Star Formation in the Central 400 pc of the Milky Way: Evidence for a Population of Massive YSOs
• Tracing the long bar with red-clump giants
• The long Galactic bar as seen by UKIDSS Galactic Plane Survey
• GBT Multiwavelength Survey of the Galactic Center Region
• The 200-pc Molecular Cylinder in the Galactic Centre
• Molecular Lines of 13 Galactic Infrared Bubble Regions

Cited by in corpus (8)

• The Mopra Southern Galactic Plane CO Survey - Data Release 3
• SPLASH: The Southern Parkes Large-Area Survey in Hydroxyl -- Data Description & Release
• 3-D CMZ IV: Distinguishing Near vs. Far Distances in the Galactic Center Using Spitzer and Herschel
• Galactic center gamma-ray production by cosmic rays from stellar winds and Sgr A East
• Modeling the Galactic center gamma-ray emission with more realistic cosmic-ray dynamics
• Cosmic rays, gas and dust in the Central Molecular Zone I -- $X_{CO}$ factors, cosmic-ray densities and dust opacities
• 3D CMZ V: A new orbital model of our Galaxy's Center, informed by data across the electromagnetic spectrum
• High Energy Emission from the Galactic Center