Bayesian inference of three-dimensional gas maps: II. Galactic HI

Abstract

The 21-cm emission from atomic hydrogen (HI) is one of the most important tracers of the structure and dynamics of the interstellar medium. Thanks to Galactic rotation, the line is Doppler shifted and, assuming a model for the velocity field, data from gas line surveys can be deprojected along the line of sight. However, given our vantage point in the Galaxy, such a reconstruction suffers from a number of ambiguities. Here, we argue that those can be cured by exploiting the spatial coherence of the gas density that is implied by the physical processes shaping it. We have adopted a Bayesian inference framework that allows reconstructing the three-dimensional map of HI and quantifying its uncertainty. We employ data from the HI4PI compilation to produce three-dimensional maps of Galactic HI. The reconstructed density shows structure on a variety of scales. In particular, some spurs and spiral arms can be identified with ease. We discuss the morphology of the surface mass density and the radial and vertical profiles. The reconstructed three-dimensional HI densities are available at https://doi.org/10.5281/zenodo.5956696.

Appendix with discussions on dust and gas correlations added

References in corpus (17)

• HI4PI: A full-sky HI survey based on EBHIS and GASS
• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• Understanding Galaxy Evolution through Emission Lines
• The Vertical Structure of the Outer Milky Way HI Disk
• The Spiral Structure of the Outer Milky Way in Hydrogen
• GASS: The Parkes Galactic All-Sky Survey. Update: improved correction for instrumental effects and new data release
• Gas flow in barred potentials
• 3D Distribution of Molecular Gas in the Barred Milky Way
• Distribution and kinematics of atomic and molecular gas inside the Solar circle
• Gamma rays as probes of cosmic-ray propagation and interactions in galaxies
• Unified Radio Interferometric Calibration and Imaging with Joint Uncertainty Quantification
• Tracing the Spiral Structure of the Outer Milky Way with Dense Atomic Hydrogen Gas
• Simulating the Galactic Multi-messenger Emissions with HERMES
• Kinetic Tomography I: A Method for Mapping the Milky Way's Interstellar Medium in Four Dimensions
• Bayesian inference of three-dimensional gas maps: I. Galactic CO
• Optical reconstruction of dust in the region of SNR RX J1713.7-3946 from astrometric data

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