Hydrodynamical Simulations of the Barred Spiral Galaxy NGC 1365

Lindblad, P. A. B.; Lindblad, P. O.; Athanassoula, E.

doi:10.1017/s0252921100050119

Cited by 67 publications

(95 citation statements)

References 2 publications

(2 reference statements)

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“…The existence of strong friction is in agreement with the theoretical prediction by Weinberg (1985), with earlier fully self-consistent simulations by Sellwood (1980) using a coarse grid, by Athanassoula (1996) using a di †erent N-body method, and others (e.g., Hernquist & Weinberg 1992). We also Ðnd that all our bars slow down as they lose angular momentum, a nontrivial result since bars are not rigid objects and could conceivably spin up (e.g., as a binary star) as angular momentum is lost.…”

Section: Summary Of Principal Resultssupporting

confidence: 91%

“…Figure 7 shows that the value of R reached by t \ 1000 correlates strongly with the angular momentum content of the halo. As found previously by Athanassoula (1996), the bars in models with retrograde halos are more strongly braked, while those in prograde halos are less so, in comparison with the nonrotating case. Nevertheless, even when direct rotation in the halo is maximized, R \ 1.7^0.4 by the end of the run despite the fact that the bar was weaker.…”

Section: Halo Rotationsupporting

confidence: 85%

See 1 more Smart Citation

Constraints from Dynamical Friction on the Dark Matter Content of Barred Galaxies

Debattista

Sellwood

2000

ApJ

526

631

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We show that bars in galaxy models having halos of moderate density and a variety of velocity distributions all experience a strong drag from dynamical friction unless the halo has large angular momentum in the same sense as the disk. The frictional drag decreases the bar pattern speed, driving the corotation point out to distances well in excess of those estimated in barred galaxies. The halo angular momentum required to avoid strong braking is unrealistically large, even when rotation is conÐned to the inner halo only. We conclude, therefore, that bars are able to maintain their observed high pattern speeds only if the halo has a central density low enough for the disk to provide most of the central attraction in the inner galaxy. We present evidence that this conclusion holds for all bright galaxies.

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Section: Summary Of Principal Resultssupporting

confidence: 91%

Section: Halo Rotationsupporting

confidence: 85%

Constraints from Dynamical Friction on the Dark Matter Content of Barred Galaxies

Debattista

Sellwood

2000

ApJ

526

631

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“…This result is in agreement with earlier numerical works that proposed spiral arms having a pattern speed smaller than that of a bar (e.g. Sellwood & Sparke 1988;Lindblad et al 1996;Sellwood & Wilkinson 1993;Tagger et al 1987).…”

Section: Discussionsupporting

confidence: 93%

Magnetic Fields and Radio Polarization of Barred Galaxies

Otmianowska-Mazur

Elstner

2003

The Evolution of Galaxies

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Abstract.A three-dimensional (3D) MHD model is applied to simulate the evolution of a large-scale magnetic field in a barred galaxy possessing a gaseous halo extending to about 2.8 kpc above the galactic plane. As the model input we use a time-dependent velocity field of molecular gas resulting from self-consistent 3D N-body simulations of a galactic disk. We assume that the gaseous halo rotates differentially co-rotating with the disk or decreasing its velocity in the Z direction. The dynamo process included in the model yields the amplification of the magnetic field as well as the formation of field structures high above the galactic disk. The simulated magnetic fields are used to construct the models of a high-frequency (Faraday rotation-free) polarized radio emission that accounts for effects of projection and limited resolution, and is thus suitable for direct comparison with observations. We found that the resultant magnetic field correctly reproduces the observed structures of polarization B-vectors, forming coherent patterns well aligned with spiral arms and with the bar. The process initializing a wave-like behavior of the magnetic field, which efficiently forms magnetic maxima between the spiral arms, is demonstrated. The inclusion of the galactic halo constitutes a step towards a realistic model of galactic magnetic fields that includes as many dynamical components as needed for a realistic description.

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“…JvM95 estimated Ω p by identifying possible signs of corotation and Lindblad resonances in the morphology and kinematics of NGC 1365. Lindblad et al (1996) estimated Ω p by matching barred spiral galaxy models to observations. The pattern speed of a model was set by an assumed corotation radius just outside the end of the bar.…”

Section: Comparison With Previous Estimates Of ω Pmentioning

confidence: 99%

The Shearing H I Spiral Pattern of NGC 1365

Speights¹,

Westpfahl²

2011

ApJ

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The Tremaine-Weinberg equations are solved for a pattern speed that is allowed to vary with radius. The solution method transforms an integral equation for the pattern speed to a least-squares problem with well-established procedures for statistical analysis. The method applied to the H i spiral pattern of the barred, grand-design galaxy NGC 1365 produces convincing evidence for a radial dependence in the pattern speed. The pattern speed behaves approximately as 1/r and is very similar to the material speed. There are no clear indications of corotation or Lindblad resonances. Tests show that the results are not selection biased, and that the method is not measuring the material speed. Other methods of solving the Tremaine-Weinberg equations for shearing patterns are found to produce results in agreement with those obtained using the current method. Previous estimates that relied on the assumptions of the density-wave interpretation of spiral structure are inconsistent with the results obtained using the current method. The results are consistent with spiral structure theories that allow for shearing patterns, and contradict fundamental assumptions in the density-wave interpretation that are often used for finding spiral arm pattern speeds. The spiral pattern is winding on a characteristic timescale of ∼500 Myr.

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Hydrodynamical Simulations of the Barred Spiral Galaxy NGC 1365

Cited by 67 publications

References 2 publications

Constraints from Dynamical Friction on the Dark Matter Content of Barred Galaxies

Constraints from Dynamical Friction on the Dark Matter Content of Barred Galaxies

Magnetic Fields and Radio Polarization of Barred Galaxies

The Shearing H I Spiral Pattern of NGC 1365

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