The Vertical Structure of the Outer Milky Way HI Disk

Abstract

We examine the outer Galactic HI disk for deviations from the b=0 plane by constructing maps of disk surface density, mean height, and thickness. We find that the Galactic warp is well described by a vertical offset plus two Fourier modes of frequency 1 and 2, all of which grow with Galactocentric radius. Adding the m=2 mode accounts for the large asymmetry between the northern and southern warps. We use a Morlet wavelet transform to investigate the spatial and frequency localization of higher frequency modes; these modes are often referred to as "scalloping." We find that the m=10 and 15 scalloping modes are well above the noise, but localized; this suggests that the scalloping does not pervade the whole disk, but only local regions.

Accepted by ApJ. 17 pages, 18 figures. Color maps are available at http://astron.berkeley.edu/~elevine

References in corpus (1)

• A Magellanic Origin for the Warp of the Galaxy

Cited by in corpus (39)

• The Role of Pressure in GMC Formation II: The H_2 - Pressure Relation
• Strongly baryon-dominated disk galaxies at the peak of galaxy formation ten billion years ago
• The observed spiral structure of the Milky Way
• The Spiral Structure of the Outer Milky Way in Hydrogen
• Dark matter in the Milky Way, II. the HI gas distribution as a tracer of the gravitational potential
• Asymmetries in the inner regions of LCDM haloes
• 3D Distribution of Molecular Gas in the Barred Milky Way
• A 3D extinction map of the Northern Galactic Plane based on IPHAS photometry
• Lopsided Spiral Galaxies
• High-Redshift Galaxy Kinematics: Constraints on Models of Disk Formation
• Flare in the Galactic stellar outer disc detected in SDSS-SEGUE data
• Cepheid Variables in the Flared Outer Disk of our Galaxy
• The distribution of gas in the Local Group from constrained cosmological simulations: the case for Andromeda and the Milky Way galaxies
• The evolution of the Milky Way: New insights from open clusters
• Parallaxes of Star Forming Regions in the Outer Spiral Arm of the Milky Way
• Distribution and kinematics of atomic and molecular gas inside the Solar circle
• Three Dimensional Hydrodynamic Simulations of Multiphase Galactic Disks with Star Formation Feedback: II. Synthetic HI 21 cm Line Observations
• Estimation of galactic model parameters in high latitudes with SDSS
• HST/COS Observations of Ionized Gas Accretion at the Disk-halo Interface of M33
• Tracing the Spiral Structure of the Outer Milky Way with Dense Atomic Hydrogen Gas
• Diffuse Gamma Rays from the Galactic Plane: Probing the "GeV Excess" and Identifying the "TeV Excess"
• Vertical velocities from proper motions of red clump giants
• Spontaneous generation of bending waves in isolated Milky Way-like discs
• The deep OB star population in Carina from the VST Photometric H$\alpha$ Survey (VPHAS+)
• Estimation of Galactic model parameters in high latitudes with 2MASS
• Open clusters and associations in the Gaia era
• An analysis of star formation with Herschel in the Hi-GAL Survey. II. The tips of the Galactic bar
• Characterizing the Galactic warp with Gaia: I. The tilted ring model with a twist
• Exploring cloudy gas accretion as a source of interstellar turbulence in the outskirts of disks
• The thickness of HI in galactic discs under MOND: theory and application to the Galaxy
• The Distant Outer Gas Arm Between l=35d and l=45d
• Milky Way Kinematics. II. A uniform inner Galaxy HI terminal velocity curve
• Kinematics of Stars in Kapteyn Selected Area 71: Sampling the Monoceros and Sagittarius Tidal Streams
• A Map of the Local Velocity Substructure in the Milky Way Disk
• A High-Velocity Cloud Impact Forming a Supershell in the Milky Way
• Astrophysics in 2006
• Azimuthal dependence of the density distribution in outer galactic discs accreting intergalactic flows
• The age-kinematical features in the Milky Way outer disk
• Magnetic flux density from the relative circular motion of stars and partially ionized gas in the Galaxy mid-plane vicinity