A New Multi-Tracer Approach to Defining the Spiral arm width in the Milky Way

Abstract

We analyze recent observations of the spiral arm width in the Milky Way, as a function of the galactic radius, and we compare this relation with the prediction from the density wave theory. We use the following method: in each spiral arm, we concentrate on the separation (or offset) between the starforming region (radio masers) near the shock front of a density wave, and the aged star region (diffuse CO gas) near the potential minimum of a density wave; we take this separation between these two tracers as the arm width. New results: we find a typical separation (maser to diffuse CO gas) near 250 +/- 50 pc, and an increase of this separation with galactic radius of about 25 +/- 5 pc per kpc. We note that, as expected, this separation is somewhat smaller than that found earlier between the dust lane and the aged star region. Overall, these results supports the basics of a density wave.

23 pages MS, 7 figures, 3 tables, 33 references, 6600 words, 4 equations. Accepted for publications

References in corpus (12)

• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• Dawes Review 4: Spiral Structures in Disc Galaxies
• Kinematic Distances to Molecular Clouds identified in the Galactic Ring Survey
• Mapping Spiral Structure on the far side of the Milky Way
• Catalog of observed tangents to the spiral arms in the Milky Way galaxy
• A guided map to the Spiral arms in the galactic disk of the Milky Way
• Recent advances in the determination of some Galactic constants in the Milky Way
• Constraining the pitch angle of the Galactic spiral arms in the Milky Way
• Statistics on 24 spiral galaxies having different observed arm locations using different arm tracers
• The Norma spiral arm: large-scale pitch angle
• Distance and proper motion measurement of water masers in Shapless 269 IRS 2w
• Resolving the distance controversy for Sharpless 269: A possible kink in the outer arm

Cited by in corpus (4)

• A low density-wave spiral pattern speed, from the tracer separations (age gradient) across a spiral arm in the Milky Way
• Catalog of spiral arm Tangents (Galactic Longitudes) in the Milky Way, and the Age Gradient based on various arm tangents
• The Steady-State Multi-TeV Diffuse Gamma-Ray Emission Predicted with GALPROP and Prospects for the Cherenkov Telescope Array
• The Observed Age Gradient in the Milky Way -- as a Test for theories of spiral arm structure