Three-Dimensional Distribution of the ISM in the Milky Way Galaxy: I. The H I Disk

By H. Nakanishi, Y. Sofue. 2003

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We derived the three-dimensional distribution of H I gas in the Milky Way Galaxy using the latest H I survey data cubes and rotation curves. The distance of the H I gas was determined by the kinematic distance using a rotation curve. We solved the near–far problem in the inner Galaxy by a fitting method which involves introducing a model of vertical H I distribution. In our resultant maps we could trace three prominent arms: the Sagittarius–Carina arm, the Perseus arm, and the Outer arm. These three arms were found to be logarithmic spiral arms. The pitch angles of the Sagittarius–Carina, Perseus, and Outer arms were estimated to be about 11 ◦ ,1 8 ◦ ,a nd 7 ◦ , respectively. The Sun is located in a region rich in H I gas between the Sagittarius–Carina arm and the Perseus arm. The H I disk shows large and asymmetric warping in the outer disk: the H I disk goes up to about 1.5kpc above the Galactic plane in the northern hemisphere, and down to about 1kpc in the southern hemisphere, which means asymmetric warping. The inner H I disk is also found to be tilting. The radius of the HI disk is about 17kpc and the H I mass within this radius is estimated to be 2.5×10 9 M� , which corresponds to 1.5% of the dynamical mass predicted from the rotation curve. We also found that the H I outskirt is largely swelling in the fourth quadrant, and hence the Galaxy is significantly lopsided. The scale-height of the H I layer increases with the radius, and is correlated with the H I volume density at the centroid of the H I layer.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/d4a7fce313088e23eb8cb4d61bf58970e532dcc2

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Citations in the corpus

A General Theory of Turbulence-regulated Star Formation, from Spirals to Ultraluminous Infrared Galaxies (2005, background): “(Note that for the observational value of we are comparing the density in GMCs to the density in the spiral arms, which is a factor of 4 higher than the mean ISM density; see Nakanishi & Sofue 2003.)”
Gas flow models in the Milky Way embedded bars (2008, methodology): “…spiral arms have two arms (Bash 1981, using HII regions; Drimmel & Spergel 2001, using K-band observations; Benjamin 2008, using Spitzer), three (Nakanishi & Sofue 2003; Kulkarni et al. 1982, using HI) or four arms (Georgelin & Georgelin (1976) using HI regions; Nakanishi & Sofue (2006) using…”
The dark matter density at the Sun’s location (2010, background): “For the present work we can neglect the HI disk because its surface density, between 2 kpc and R , is 100 to 5 times smaller than the stellar surface density (Nakanishi & Sofue 2003).”
Three-Dimensional Distribution of the ISM in the Milky Way Galaxy: II. The Molecular Gas Disk (2006, methodology): “In PaperI (Nakanishi & Sofue2003), we have analyzedthe latest21-cm line survey data,andpresentedthe 3D distribution mapof H I gasin the Milk y Way Galaxy.”
Global properties of the H I distribution in the outer Milky Way - Planar and extra-planar gas (2008, methodology): “The global surface density distribution, mid plane densities and also ﬂaring depend weakly on the rotation curve (Voskes 1999; Nakanishi & Sofue 2003; Levine et al. 2006a,b) but our results are not altered signiﬁcantly as long as a nearly ﬂat rotation curve is used.”
The Spiral Arms and Interarm Separation of the Milky Way: An Updated Statistical Study (2005, methodology): “Nakanishi & Sofue (2003) used H i data to trace three prominent spiral arms and found them to be roughly logarithmic, with a range in pitch angles, assuming pure circular motions.”
Toward First-Principle Simulations of Galaxy Formation: I. How Should We Choose Star-Formation Criteria in High-Resolution Simulations of Disk Galaxies? (2008, methodology): “Nakanishi & Sofue (2003) reconstructed the three dimensional structure of HI gas of the Milky Way galaxy, by compiling three HI survey data: the Leiden/Dwingelloo survey (Hartmann & Burton 1997), Parkes survey (Kerr et al. 1986), and NRAO survey (Burton & Liszt 1983).”
GX 339—4: the distance, state transitions, hysteresis and spectral correlations (2004, background): “(ii) The maximum Galactic disc warping on the southern hemisphere corresponds to the azimuthal angle of Θ = 260◦, where the warping starts at the radial distance from the Galactic Center of R = 12 kpc and the Hi disc is bending down to z = −1 kpc at R = 16 kpc (Nakanishi & Sofue 2003).”
Unified Rotation Curve of the Galaxy — Decomposition into de Vaucouleurs Bulge, Disk, Dark Halo, and the 9-kpc Rotation Dip — (2008, methodology): “Since the observed data are obtained for stars and gas within several kpc from the Sun, it is possible that this ring represents a density wave corresponding to the Perseus Arm (e.g. Nakanishi and Sofue 2003, 2006).”
The observed spiral structure of the Milky Way (2014, background): “The spiral structure derived from diffuse HI and CO distributions is far from clear at present (e.g., see Nakanishi & Sofue 2003, 2006).”
FORMING REALISTIC LATE-TYPE SPIRALS IN A ΛCDM UNIVERSE: THE ERIS SIMULATION (2011, methodology): “Eris’ H I mass is MHI = 1.9 × 109 M , comparable to the H I mass estimated for the Milky Way disk by Nakanishi & Sofue (2003), but smaller than the value of ∼ 5×109 M given by Wolfire et al. (2003).”
Dark matter in the Milky Way II. The HI gas distribution as a tracer of the gravitational potential (2007, methodology): “The depression in the flaring curve at 12< R < 25 kpc has been seen before, see e.g. the recent papers by Nakanishi & Sofue (2003) and Levine et al. (2006a), but the effect shows up as most pronounced in Fig.”