Tracing the Spiral Structure of the Outer Milky Way with Dense Atomic Hydrogen Gas

Abstract

We present a new face-on map of dense neutral atomic hydrogen (HI) gas in the outer Galaxy. Our map has been produced from the Leiden/Argentine/Bonn (LAB) HI 21-cm line all-sky survey by finding intensity maxima along every line of sight and then by projecting them on the Galactic plane. The resulting face-on map strikingly reveals the complex spiral structure beyond the solar circle, which is characterized by a mixture of distinct long arcs of HI concentrations and numerous 'interarm' features. The comparison with more conventional spiral tracers confirms the nature of those long arc structures as spiral arms. Our map shows that the HI spiral structure in the outer Galaxy is well described by a four-arm spiral model (pitch angle of 12 deg) with some deviations, and gives a new insight into identifying HI features associated with individual arms.

arXiv comment24 pages, 10 figures, 3 tables; accepted for publication in PASP

References in corpus (29)

• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• Trigonometric Parallaxes of High Mass Star Forming Regions: the Structure and Kinematics of the Milky Way
• The persistent cosmic web and its filamentary structure I: Theory and implementation
• The WISE Catalog of Galactic HII Regions
• The Distance to the Perseus Spiral Arm in the Milky Way
• The Structure of the Milky Way's Bar Outside the Bulge
• A Parallax-based Distance Estimator for Spiral Arm Sources
• The observed spiral structure of the Milky Way
• Three-Dimensional Distribution of the ISM in the Milky Way Galaxy: I. The HI Disk
• The Vertical Structure of the Outer Milky Way HI Disk
• The Spiral Structure of the Outer Milky Way in Hydrogen
• Parallaxes for W49N and G048.60+0.02: Distant Star Forming Regions in the Perseus Spiral Arm
• Three-Dimensional Distribution of the ISM in the Milky Way Galaxy: III. The Total Neutral Gas Disk
• A high sensitivity HI survey of the sky at delta < -25 deg Final data release
• A Molecular Spiral Arm in the Far Outer Galaxy
• Spiral structure in the outer Galactic disk. I. The Third Galactic Quadrant
• The local spiral structure of the Milky Way
• A Possible Extension of the Scutum-Centaurus Arm into the Outer Second Quadrant
• The Milky Way Spiral Structure Parameters from Data on Masers and Selected Open Clusters
• A Distant Extended Spiral Arm in the Fourth Quadrant of the Milky Way
• Scalable Automated Detection of Spiral Galaxy Arm Segments
• On the Spiral Structure of the Milky Way Galaxy
• Pitch angle variations in spiral galaxies
• Different studies of the global pitch angle of the Milky Way's spiral arms
• Characteristics of Spiral Arms in Late-type Galaxies
• H-alpha kinematics of S4G spiral galaxies-II. Data description and non-circular motions
• Gaseous Spiral Structure and Mass Drift in Spiral Galaxies
• An Outer Arm in the Second Galactic Quadrant: Structure
• On the Rotation Speed of the Milky Way Determined from HI Emission

Cited by in corpus (30)

• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• A three-dimensional map of the Milky Way using classical Cepheid variable stars
• Kinematic Distances: A Monte Carlo Method
• Mapping the Galactic Metallicity Gradient with Open Clusters: The State-of-the-Art and Future Challenges
• The Galactic spiral structure as revealed by O- and early B-type stars
• Local Simulations of Spiral Galaxies with the TIGRESS Framework: I. Star Formation and Arm Spurs/Feathers
• The Galactic dynamics revealed by the filamentary structure in atomic hydrogen emission
• The spiral structure in the Solar neighborhood
• Constraining the pitch angle of the Galactic spiral arms in the Milky Way
• Into the Darkness: Classical and Type II Cepheids in the Zona Galactica Incognita
• Parallaxes for star forming regions in the inner Perseus spiral arm
• Using classical Cepheids to study the far side of the Milky Way disk. II. The spiral structure in the first and fourth Galactic quadrants
• The SEDIGISM survey: The influence of spiral arms on the molecular gas distribution of the inner Milky Way
• GASKAP Pilot Survey Science II: ASKAP Zoom Observations of Galactic 21-cm Absorption
• Highly Embedded 8 micron Cores of Star Formation in the Spiral Arms and Filaments of 15 Nearby Disk Galaxies
• Spatially Coherent 3D Distributions of HI and CO in the Milky Way
• OGHReS: Large-scale filaments in the outer Galaxy
• Bayesian inference of three-dimensional gas maps: II. Galactic HI
• Peering into the Milky Way by FAST: I. Exquisite HI structures in the inner Galactic disk from the piggyback line observations of the FAST GPPS survey
• Resolving the distance controversy for Sharpless 269: A possible kink in the outer arm
• A low density-wave spiral pattern speed, from the tracer separations (age gradient) across a spiral arm in the Milky Way
• Exploring the structure and kinematics of the Milky Way through A stars
• VERA astrometry toward the Perseus arm gap
• Distributions and Physical Properties of Molecular Clouds in the Third Galactic Quadrant: $l$ = [219.75, 229.75]${}^{\circ }$ and $b$ = [-5.25, 5.25]${}^{\circ }$
• The High Mass Slope of the IMF
• Spiral arms and the angular momentum gap in Milky Way Cepheids
• GS242-03+37: a lucky survivor in the galactic gravitational field
• KSP-OT-201611a: A Distant Population II Dwarf Nova Candidate Discovered by the KMTNet Supernova Program
• Interarm islands in the Milky Way -- the one near the Cygnus spiral arm
• Carbon Monoxide Observations Toward Star Forming Regions in the Outer Scutum-Centaurus Spiral Arm