The Vertical Structure of the Outer Milky Way H I Disk

By E. S. Levine, L. Blitz, C. Heiles. 2006

175 citations recorded by the source corpus.

We examine the outer Galactic H I 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 m = 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.

Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/1b3f00f462de4126bbe1cacb3fe6df63d6be2b81

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Statistical and Nonlinear Physics

Citations in the corpus

Painting a portrait of the Galactic disc with its stellar clusters (2020, background): “The warping of the Galactic plane is particularly visible in the HI gas distribution (Burke 1957; Kerr 1957; Westerhout 1957; Levine et al. 2006; Kalberla et al. 2007) and is now known to be a common feature in disc galaxies (e.g. Sancisi 1976; A1, page 13 of 17 Briggs 1990; Sánchez-Saavedra et al.…”
The influence of Sagittarius and the Large Magellanic Cloud on the stellar disc of the Milky Way Galaxy (2017, result): “Nonetheless, it should be noted that the structure of the HI disc has been derived using kinematically inferred distances (Levine et al. 2006).”
Global properties of the H I distribution in the outer Milky Way - Planar and extra-planar gas (2008, methodology): “Surface densities and mid-plane volume densities are a ﬀ ected by spiral structure, but di ﬀ erences between north and south need to be explained by an asymmetric disk (Levine et al. 2006a,b; Kalberla et al. 2007).”
The Role of Pressure in GMC Formation II: The H2-Pressure Relation (2006, methodology): “Finally, we scale ΣHI by 1.5 to account for the presence of high latitude gas, based on the results beyond the Solar circle from Levine et al. (2006).”
Cepheid variables in the flared outer disk of our galaxy (2014, methodology): “two estimates of the distance modulus, (μ0)VI and (μ0)JK—derived, respectively, from equations (1) and (2) and equations (3) and (4)—and the interstellar extinction corrections, AI and AK (Extended Data Table 2).”
KINEMATICAL AND CHEMICAL VERTICAL STRUCTURE OF THE GALACTIC THICK DISK. II. A LACK OF DARK MATTER IN THE SOLAR NEIGHBORHOOD, (2012, methodology): “Levine et al. (2006) also used a flat curve to measure the Galactic density distribution.”
Gaseous Galaxy Halos (2012, background): “In some regions, there are kpc extensions from the disk due to the presence of IVCs or the Galactic warp (Levine et al., 2006; Kalberla & Dedes, 2008).”
The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream (2018, result): “…∼40 kpc penetrating into the inner regions of the Galaxy, resulting in torques warping the disc with similar shape and line of nodes as the observed HI warp (Levine et al. 2006), in agreement with earlier expectations from linear perturbation theory (e.g. Weinberg 1998; Weinberg & Blitz 2006).”
GASS: THE PARKES GALACTIC ALL-SKY SURVEY. I. SURVEY DESCRIPTION, GOALS, AND INITIAL DATA RELEASE (2009, methodology): “…of the λ = 21 cm spectral line in 1951 by Ewen & Purcell (1951), it has been used repeatedly, and with continuous refinements, to explore the rotation curve and map the global structure of the Galaxy (e.g., Kerr 1962; Henderson et al. 1982; Levine et al. 2006; McClure-Griffiths & Dickey 2007).”
Red Clump Stars from LAMOST II: the outer disc of the Milky Way (2017, background): “With data on the HI region in the outer Galactic disc, Levine et al. (2006) found asymmetry in the warp (especially at Galactocentric azimuth 90◦ and −90◦, see figs.”
The observed spiral structure of the Milky Way (2014, background): “…is supported by observations later (e.g., Downes et al. 1980; Caswell & Haynes 1987; Englmaier & Gerhard 1999; Drimmel & Spergel 2001; Russeil 2003; Levine et al. 2006; Bobylev & Bajkova 2014), though other spiral patterns have been proposed to describe the structure of the Galaxy (see, e.g.,…”
Dark matter in the Milky Way II. The HI gas distribution as a tracer of the gravitational potential (2007, methodology): “We followed the convention used by Levine et al. (2006a) and plot the phases for the first maximum close to azimuth 90◦.”