Anisotropy in the carbon monoxide (CO) line emission across the Milky Way's disk

Abstract

We present a study of the ${}^{12}$CO(1-0) line emission anisotropy across the Milky Way's disk to examine the effect of stellar feedback and Galactic dynamics on the distribution of the dense interstellar medium. The Hessian matrix method is used to characterize the CO line emission distribution and identify the preferential orientation across line-of-sight velocity channels in the Dame et al. 2001 composite Galactic plane survey, which covers the Galactic latitude range $|b|<5^{\circ }$. The structures sampled with this tracer are predominantly parallel to the Galactic plane toward the inner Galaxy, in clear contrast with the predominantly perpendicular orientation of the structures traced by neutral atomic hydrogen (HI) emission toward the same regions. The analysis of the Galactic plane portions sampled at higher angular resolution with other surveys reveals that the alignment with the Galactic plane is also prevalent at smaller scales. We find no preferential orientation in the CO emission toward the outer Galaxy, in contrast with the preferential alignment with the Galactic plane displayed by HI in that portion of the Milky Way. We interpret these results as the combined effect of the decrease in mid-plane pressure with increasing Galactocentric radius and SN feedback lifting diffuse gas more efficiently than dense gas off the Galactic plane.

11 pages, 8 figures, 3 appendices. Submitted to A&A (04APR2025)

References in corpus (47)

• HI4PI: A full-sky HI survey based on EBHIS and GASS
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• Momentum Injection by Supernovae in the Interstellar Medium
• Physical properties of molecular clouds for the entire Milky Way disk
• Separation of anomalous and synchrotron emissions using WMAP polarization data
• The cold interstellar medium of galaxies in the Local Universe
• CO-dark gas and molecular filaments in Milky Way type galaxies
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) I: Project Overview and Initial Results
• The Milky Way Imaging Scroll Painting (MWISP): Project Details and Initial Results from the Galactic Longitude of 25.8deg to 49.7deg
• On the nature of star-forming filaments: I. Filament morphologies
• The Bones of the Milky Way
• The Cloud Factory I: Generating resolved filamentary molecular clouds from galactic-scale forces
• The SEDIGISM survey: first data release and overview of the Galactic structure
• The Hi-GAL catalogue of dusty filamentary structures in the Galactic Plane
• An application of an optimal statistic for characterising relative orientations
• A Census of Large-Scale ($\ge$ 10 pc), Velocity-Coherent, Dense Filaments in the Northern Galactic Plane: Automated Identification Using Minimum Spanning Tree
• The Star Formation Rate of the Milky Way as seen by Herschel
• The HI/OH/Recombination line survey of the inner Milky Way (THOR): data release 2 and HI overview
• Cold gas in the Milky Way's nuclear wind
• The Mass-Size Relation and the Constancy of GMC Surface Densities in the Milky Way
• The evolution of Giant Molecular Filaments
• High-velocity extended molecular outflow in the star-formation dominated luminous infrared galaxy ESO 320-G030
• Testing kinematic distances under a realistic Galactic potential
• The history of dynamics and stellar feedback revealed by the HI filamentary structure in the disk of the Milky Way
• Frequency and nature of central molecular outflows in nearby star-forming disk galaxies
• The Galactic dynamics revealed by the filamentary structure in atomic hydrogen emission
• TurbuStat: Turbulence Statistics in Python
• The Forgotten Quadrant Survey. ${}^{12}$CO and ${}^{13}$CO (1-0) survey of the Galactic Plane in the range 220°$<l<$240° -2.5°$<b<$0°
• PHANGS--JWST First Results: ISM structure on the turbulent Jeans scale in four disk galaxies observed by JWST and ALMA
• A far-IR view of the starburst driven superwind in NGC 2146
• Observational Evidence for a Thick Disk of Dark Molecular Gas in the Outer Galaxy
• The Galactic Census of High- and Medium-mass Protostars. III ${}^{12}$CO Maps and Physical Properties of Dense Clump Envelopes and their Embedding GMCs
• Did the Milky Way just light up? The recent star formation history of the Galactic disc
• Synthetic Large-Scale Galactic Filaments -- on their Formation, Physical Properties, and Resemblance to Observations
• The SEDIGISM survey: Molecular cloud morphology. I. Classification and star formation
• Fast Molecular Cloud Destruction Requires Fast Cloud Formation
• JWST MIRI and NIRCam observations of NGC 891 and its circumgalactic medium
• A comparison of the Milky Way's recent star formation revealed by dust thermal emission and high-mass stars
• On the distribution of the Cold Neutral Medium in galaxy discs
• Kinetic tomography of the Galactic plane within 1.25 kiloparsecs from the Sun. The interstellar flows revealed by HI and CO line emission and 3D dust
• JWST Observations of Starbursts: Relations between PAH features and CO clouds in the starburst galaxy M 82
• The filamentary structures in the CO emission toward the Milky Way disk
• The SEDIGISM survey: Molecular cloud morphology. II. Integrated source properties
• Cold molecular gas in the hot nuclear wind of the Milky Way
• The dynamical impact of cosmic rays in the Rhea magnetohydrodynamics simulations
• A path towards constraining the evolution of the interstellar medium and outflows in the Milky Way using APOGEE