Dawes Review 4: Spiral Structures in Disc Galaxies

Dobbs, Clare; Baba, Junichi

doi:10.1017/pasa.2014.31

Cited by 243 publications

(298 citation statements)

References 314 publications

(843 reference statements)

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“…The model does not rely on independent offsets between young stars and gaseous spiral arms, which might be created by other -not feedback-related -processes and which are a matter of ongoing research (compare, e.g., the review by Dobbs & Baba 2014).…”

Section: Discussionmentioning

confidence: 99%

²⁶Al kinematics: superbubbles following the spiral arms?

Krause

Diehl

Bagetakos

et al. 2015

A&A

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Context. High-energy resolution spectroscopy of the 1.8 MeV radioactive decay line of 26 Al with the SPI instrument onboard the INTEGRAL satellite has recently revealed that diffuse 26 Al has higher velocities than other components of the interstellar medium in the Milky Way. 26 Al shows Galactic rotation in the same sense as the stars and other gas tracers, but reaches excess velocities of up to 300 km s −1 . Aims. We investigate whether this result can be understood in the context of superbubbles, taking into account the statistics of young star clusters and H I supershells as well as the association of young star clusters with spiral arms. Methods. We derived energy output and 26 Al mass of star clusters as a function of the cluster mass by population synthesis from stellar evolutionary tracks of massive stars. Using the limiting cases of weakly and strongly dissipative superbubble expansion, we linked this to the size distribution of H I supershells and assessed the properties of possible 26 Al-carrying superbubbles. Results. 26 Al is produced by star clusters of all masses above ≈200 M , is roughly equally contributed over a logarithmic star cluster mass scale and strongly linked to the injection of feedback energy. The observed superbubble size distribution cannot be related to the star cluster mass function in a straightforward manner. To avoid the added volume of all superbubbles exceeding the volume of the Milky Way, individual superbubbles have to merge frequently. If any two superbubbles merge, or if 26 Al is injected off-centre into a larger HI supershell, we expect the hot 26 Al-carrying gas to obtain velocities of the order of the typical sound speed in superbubbles, ≈300 km s −1 before decay. For star formation coordinated by the spiral arm pattern which, inside co-rotation, is overtaken by the faster moving stars and gas, outflows from spiral arm star clusters would preferentially flow into the cavities that are inflated by previous star formation associated with this arm. These cavities would preferentially be located towards the leading edge of a given arm. Conclusions. This scenario might explain the 26 Al kinematics. The massive-star ejecta are expected to survive ≥10 6 yr before being recycled into next-generation stars.

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Section: Discussionmentioning

confidence: 99%

²⁶Al kinematics: superbubbles following the spiral arms?

Krause

Diehl

Bagetakos

et al. 2015

A&A

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“…This leads to the lack of an inner Lindblad resonance, which is believed to encourage the growth of m = 2 modes (i.e. a bar) due to the lack of a Q-barrier in the inner disc (Binney & Tremaine 1987;Combes et al 1995;Dobbs & Baba 2014). If we allowed the bulge-free models to evolve for the order of several Gyr then an inner bar component is seen to develop, but at the expense of arm structure.…”

Section: Simulations and Morphology Of Other Modelsmentioning

confidence: 99%

The morphology of the Milky Way – II. Reconstructing CO maps from disc galaxies with live stellar distributions

Pettitt¹,

Dobbs²,

Acreman³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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The arm structure of the Milky Way remains somewhat of an unknown, with observational studies hindered by our location within the Galactic disc. In the work presented here we use smoothed particle hydrodynamics (SPH) and radiative transfer to create synthetic longitude-velocity observations. Our aim is to reverse-engineer a top down map of the Galaxy by comparing synthetic longitude-velocity maps to those observed. We set up a system of N -body particles to represent the disc and bulge, allowing for dynamic creation of spiral features. Interstellar gas, and the molecular content, is evolved alongside the stellar system. A 3D-radiative transfer code is then used to compare the models to observational data. The resulting models display arm features that are a good reproduction of many of the observed emission structures of the Milky Way. These arms however are dynamic and transient, allowing for a wide range of morphologies not possible with standard density wave theory. The best fitting models are a much better match than previous work using fixed potentials. They favour a 4-armed model with a pitch angle of approximately 20• , though with a pattern speed that decreases with increasing Galactic radius. Inner bars are lacking however, which appear required to fully reproduce the central molecular zone.

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“…While a number of past numerical studies found that spirals fade out quickly over time (for a recent review see Dobbs & Baba 2014, and references therein), recent studies showed that in a stellar disc with more than a few million particles spiral arms persist for longer periods of time, indicating that previous results were suffering from discreteness effects (e.g. Fujii et al 2011;Grand et al 2012b).…”

Section: Introductionmentioning

confidence: 99%

Stellar spiral structures in triaxial dark matter haloes

Sijacki

2016

Mon. Not. R. Astron. Soc.

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We employ very high resolution simulations of isolated Milky Way-like galaxies to study the effect of triaxial dark matter haloes on exponential stellar discs. Nonadiabatic halo shape changes can trigger two-armed grand-design spiral structures which extend all the way to the edge of the disc. Their pattern speed coincides with the inner Lindblad resonance indicating that they are kinematic density waves which can persist up to several Gyr. In dynamically cold discs, grand-design spirals are swing amplified and after a few Gyr can lead to the formation of (multi-armed) transient recurrent spirals. Stellar discs misaligned to the principal planes of the host triaxial halo develop characteristic integral shaped warps, but otherwise exhibit very similar spiral structures as aligned discs. For the grand-design spirals in our simulations, their strength dependence with radius is determined by the torque on the disc, suggesting that by studying grand-design spirals without bars it may be possible to set constraints on the tidal field and host dark matter halo shape.

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Dawes Review 4: Spiral Structures in Disc Galaxies

Cited by 243 publications

References 314 publications

²⁶Al kinematics: superbubbles following the spiral arms?

²⁶Al kinematics: superbubbles following the spiral arms?

The morphology of the Milky Way – II. Reconstructing CO maps from disc galaxies with live stellar distributions

Stellar spiral structures in triaxial dark matter haloes

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Dawes Review 4: Spiral Structures in Disc Galaxies

Cited by 243 publications

References 314 publications

26Al kinematics: superbubbles following the spiral arms?

26Al kinematics: superbubbles following the spiral arms?

The morphology of the Milky Way – II. Reconstructing CO maps from disc galaxies with live stellar distributions

Stellar spiral structures in triaxial dark matter haloes

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Product

Resources

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²⁶Al kinematics: superbubbles following the spiral arms?

²⁶Al kinematics: superbubbles following the spiral arms?