Gas dynamics in the Milky Way: second pattern speed and large-scale morphology

By Nicolai Bissantz, P. Englmaier, O. Gerhard. 2002

167 citations recorded by the source corpus.

We present new gas flow models for the Milky Way inside the solar circle. We use smoothed particles hydrodynamics (SPH) simulations in gravitational potentials determined from the near-infrared (NIR) luminosity distribution of the bulge and disc, assuming a constant NIR mass-to-light ratio, with an outer halo added in some cases. The luminosity models are based on the COBE/DIRBE maps and on clump giant star counts in several bulge fields and include a spiral arm model for the disc. Gas flows in models that include massive spiral arms clearly match the observed 12 CO (l, v) diagram better than if the potential does not include spiral structure. Furthermore, models in which the luminous mass distribution and the gravitational potential of the Milky Way have four spiral arms are better fits to the observed (l, v) diagram than two-armed models. Besides single-pattern speed models we investigate models with separate pattern speeds for the bar and spiral arms. The most important difference is that in the latter case the gas spiral arms go through the bar corotation region, keeping the gas aligned with the arms there. In the (l, v) plot this results in characteristic regions that appear to be nearly devoid of gas. In single-pattern speed models these regions are filled with gas because the spiral arms dissolve in the bar corotation region. Comparing with the 12 CO data we find evidence for separate pattern speeds in the Milky Way.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/a5021af7f37c152d43b7e4cc269551f6e4ce680f

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In Astronomy and Astrophysics

1. I. Minchev
2. B. Famaey
3. O. Gerhard
4. Joss Bland-Hawthorn
5. Matthieu Portail
6. C. Wegg
7. S. McGaugh
8. J. Vallée

Citations in the corpus

• Dynamical modelling of the galactic bulge and bar: the Milky Way's pattern speed, stellar and dark matter mass distribution (2016, background): “…determinations concluded on rather large pattern speeds in the range of 50−65kms−1 kpc−1 from gas dynamics (Englmaier & Gerhard 1999; Fux 1999; Bissantz et al. 2003), continuity of a tracer stellar population (Debattista et al. 2002) or interpretation of stellar stream in the solar…”
• Spatial distribution of interstellar gas in the innermost 3 kpc of our galaxy (2007, methodology): “This is exactly what a close scrutiny of the face-on maps of Englmaier & Gerhard (1999) and Fux (1999) shows.”
• The Spiral Arms and Interarm Separation of the Milky Way: An Updated Statistical Study (2005, methodology): “Bissantz et al. (2003) employedmany smoothed particle hydrodynamics simulations to fit the molecular CO gas and nearinfrared luminosity.”
• Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensions (2011, methodology): “In addition to the above challenge, the distribution of dark subhalos around the Galaxy is also predicted by ΛCDM to be isotropic, or quasi-isotropic.”
• The Galactic abundance gradient from Cepheids - V. Transition zone between 10 and 11 kpc (2004, background): “It is worth noting that Bissantz et al. (2003) emphazise that the real difference between their two theoretical models for Ωp = 20 and 40 km s−1 kpc−1 “are too small to determine the spatial arm pattern speed reliably”.”
• The structure of the Milky Way's bar outside the bulge (2015, background): “It influences for example the disk outside the bar (Minchev & Famaey 2010), the kinematics in the solar neighbourhood (Dehnen 2000), and the observed non-circular gas flow (Bissantz et al. 2003).”
• A NEW MECHANISM FOR RADIAL MIGRATION IN GALACTIC DISKS: SPIRAL–BAR RESONANCE OVERLAP (2009, methodology): “There are also indications from the gas flow in the inner Galaxy that the MW has stronger spiral arms, where the amplitude in the mass density is larger by a factor of 1.5 than its amplitude in the near-infrared luminosity density (see Bissantz et al. 2003; Famaey and Binney 2005).”
• Gas flow models in the Milky Way embedded bars (2008, methodology): “Other Galactic dynamics models have been mainly devoted to larger scales, from the works of Mulder & Liem (1986) and Wada et al. (1994) to the more recent works by Fux (1999); Englmaier & Gerhard (1999); Weiner & Sellwood (1999) and Bissantz et al. (2003).”
• A Massive Cluster of Red Supergiants at the Base of the Scutum-Crux Arm (2007, background): “…by Nakashima & Deguchi (2006), the inferred distances for the objects put them close to where the spiral arms meet the Galactic bulge, roughly the corota- tion radius of the bulge bar (Bissantz et al. 2003), and in the middle of the proposed high-density ‘‘stellar ring’’ (Bertelli et al. 1995).”
• The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, background): “Englmaier & Gerhard (1999) and Bissantz et al. (2003) estimated 55–65 km s−1 kpc−1 (RCR = 3.4 ± 0.3 kpc), matching the terminal velocity curve, spiral arm tangents, and ridges in the lv-plot.”