Gravitational Bar and Spiral Arm Torques fromKs-band Observations and Implications for the Pattern Speeds

ABSTRACT With backwards orbit integration, we estimate birth locations of young stellar associations and moving groups identified in the solar neighbourhood that are younger than 70 Myr. The birth locations of most of these stellar associations are at a smaller galactocentric radius than the Sun, implying that their stars moved radially outwards after birth. Exceptions to this rule are the Argus and Octans associations, which formed outside the Sun’s galactocentric radius. Variations in birth heights of the stellar associations suggest that they were born in a filamentary and corrugated disc of molecular clouds, similar to that inferred from the current filamentary molecular cloud distribution and dust extinction maps. Multiple spiral arm features with different but near corotation pattern speeds and at different heights could account for the stellar association birth sites. We find that the young stellar associations are located in between peaks in the radial/tangential (UV) stellar velocity distribution for stars in the solar neighbourhood. This would be expected if they were born in a spiral arm, which perturbs stellar orbits that cross it. In contrast, stellar associations seem to be located near peaks in the vertical phase-space distribution, suggesting that the gas in which stellar associations are born moves vertically together with the low-velocity dispersion disc stars.

Download Full-text

How do different spiral arm models impact the ISM and GMC population?

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2242 ◽

2020 ◽

Vol 498 (1) ◽

pp. 1159-1174

Author(s):

Alex R Pettitt ◽

Clare L Dobbs ◽

Junichi Baba ◽

Dario Colombo ◽

Ana Duarte-Cabral ◽

...

Keyword(s):

Radial Dependence ◽

Spiral Arms ◽

Star Forming ◽

Gas Kinematics ◽

Cloud Properties ◽

Grand Design ◽

Pattern Speeds ◽

Galactic Spiral ◽

Spiral Model ◽

Spiral Arm

ABSTRACT The nature of galactic spiral arms in disc galaxies remains elusive. Regardless of the spiral model, arms are expected to play a role in sculpting the star-forming interstellar medium (ISM). As such, different arm models may result in differences in the structure of the ISM and molecular cloud properties. In this study, we present simulations of galactic discs subject to spiral arm perturbations of different natures. We find very little difference in how the cloud population or gas kinematics vary between the different grand design spirals, indicating that the ISM on cloud scales cares little about where spiral arms come from. We do, however, see a difference in the interarm/arm mass spectra, and minor differences in tails of the distributions of cloud properties (as well as radial variations in the stellar/gaseous velocity dispersions). These features can be attributed to differences in the radial dependence of the pattern speeds between the different spiral models, and could act as a metric of the nature of spiral structure in observational studies.

Download Full-text

Spiral arm amplitude variations and pattern speeds in the grand design galaxies M51, M81, and M100

The Astrophysical Journal ◽

10.1086/167733 ◽

1989 ◽

Vol 343 ◽

pp. 602 ◽

Cited By ~ 91

Author(s):

Bruce G. Elmegreen ◽

Philip E. Seiden ◽

Debra Meloy Elmegreen

Keyword(s):

Grand Design ◽

Pattern Speeds ◽

Spiral Arm

Download Full-text

Theoretical investigation for the relation (supermassive black hole mass)–(spiral arm pitch angle): a correlation for galaxies with classical bulges

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/571/1/012118 ◽

2019 ◽

Vol 571 ◽

pp. 012118

Author(s):

Ismaeel A Al-Baidhany ◽

Sami S Chiad ◽

Wasmaa A Jabbar ◽

Rasha A Hussein ◽

Firas F K Hussain ◽

...

Keyword(s):

Black Hole ◽

Theoretical Investigation ◽

Pitch Angle ◽

Black Hole Mass ◽

Supermassive Black Hole ◽

Spiral Arm

Download Full-text

TESTING THE LINK BETWEEN TERRESTRIAL CLIMATE CHANGE AND GALACTIC SPIRAL ARM TRANSIT

The Astrophysical Journal ◽

10.1088/0004-637x/705/2/l101 ◽

2009 ◽

Vol 705 (2) ◽

pp. L101-L103 ◽

Cited By ~ 29

Author(s):

Andrew C. Overholt ◽

Adrian L. Melott ◽

Martin Pohl

Keyword(s):

Climate Change ◽

Galactic Spiral ◽

Spiral Arm

Download Full-text

The Dark Matter Halo Density Profile, Spiral Arm Morphology, and Supermassive Black Hole Mass of M33

ISRN Astronomy and Astrophysics ◽

10.5402/2011/725697 ◽

2011 ◽

Vol 2011 ◽

pp. 1-8 ◽

Cited By ~ 6

Author(s):

Marc S. Seigar

Keyword(s):

Black Hole ◽

Dark Matter ◽

Density Profile ◽

Pitch Angle ◽

Rotation Curve ◽

Dark Matter Halo ◽

Black Hole Mass ◽

Supermassive Black Hole ◽

Virial Mass ◽

Spiral Arm

We investigate the dark matter halo density profile of M33. We find that the HI rotation curve of M33 is best described by an NFW dark matter halo density profile model, with a halo concentration of and a virial mass of . We go on to use the NFW concentration of M33, along with the values derived for other galaxies (as found in the literature), to show that correlates with both spiral arm pitch angle and supermassive black hole mass.

Download Full-text

Is High-Velocity Cloud Complex C Associated with the Galactic Warp?

Publications of the Astronomical Society of Australia ◽

10.1071/as03028 ◽

2003 ◽

Vol 20 (3) ◽

pp. 263-269 ◽

Cited By ~ 4

Author(s):

Daisuke Kawata ◽

Christopher Thom ◽

Brad K. Gibson

Keyword(s):

High Latitude ◽

High Velocity ◽

Large Magellanic Cloud ◽

Alternative Interpretation ◽

North Polar ◽

Gas Cloud ◽

Cloud Complex ◽

Galactic Warp ◽

Velocity Cloud ◽

Spiral Arm

AbstractWe test the hypothesis that high-velocity gas cloud Complex C is actually a high-latitude spiral arm extension in the direction of the Galactic warp, as opposed to the standard interpretation — that of a once extragalactic, but now infalling, gas cloud. A parallel Tree N-body code was employed to simulate the tidal interaction of a satellite perturber with the Milky Way. We find that a model incorporating a perturber of the mass of the Large Magellanic Cloud on a south to north polar orbit, crossing the disk at ˜15 kpc, does yield a high-velocity, high-latitude extension consistent with the spatial, kinematical, and column density properties of Complex C. Unless this massive satellite remains undiscovered because of either a fortuitous alignment with the Galactic bulge (feasible within the framework of the model), or the lack of any associated baryonic component, we conclude that this alternative interpretation appears unlikely.

Download Full-text