Vertical gradients of azimuthal velocity in a global thin-disc model of spiral galaxies NGC 2403, NGC 4559, NGC 4302 and NGC 5775

Jałocha, J.; Bratek, Łukasz; Kutschera, M.; Skindzier, Piotr

doi:10.1111/j.1365-2966.2010.17906.x

Cited by 6 publications

(4 citation statements)

References 11 publications

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“…We recently applied our gradient estimation method to six galaxies with available measurements of the vertical gradient of rotation (Jalocha et al 2010; Jałocha et al 2011). We found our predictions of the gradient value to agree within error bars with measurements.…”

Section: Vertical Gradient Of Rotation and Magnetic Fieldmentioning

confidence: 99%

The role of large-scale magnetic fields in galaxy NGC 891: can magnetic fields help to reduce the local mass-to-light ratio in the galactic outskirts?

Jałocha

Bratek

Pękala

et al. 2012

Monthly Notices of the Royal Astronomical Society

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We address the problem of the influence of large‐scale magnetic fields on galactic rotation for the example of the spiral galaxy NGC 891. Based on its rotation curve and the surface density of H i we determine, in the framework of the global disc model, the surface density of matter. Then, based on the surface brightness, we determine the corresponding profile of the local mass‐to‐light ratio. We also model the vertical gradient of azimuthal velocity in the quasi‐circular‐orbit approximation, and compare it with measurements. We discuss what factors may influence the rotation of matter in NGC 891 and how this can translate to changes in the profile of the local mass‐to‐light ratio. In particular, we discuss the possible effect of magnetic fields on the motion of ionized gas, and, consequently, on the determination of the profile of the local mass‐to‐light ratio. Finally, we put forward the hypothesis that the asymmetry in magnetic fields observed in NGC 891 might be responsible for the observed anomalous behaviour of the vertical gradient.

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Section: Vertical Gradient Of Rotation and Magnetic Fieldmentioning

confidence: 99%

The role of large-scale magnetic fields in galaxy NGC 891: can magnetic fields help to reduce the local mass-to-light ratio in the galactic outskirts?

Jałocha

Bratek

Pękala

et al. 2012

Monthly Notices of the Royal Astronomical Society

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“…In the present paper we use microlensing measurements to constrain the disk width and we compare the resulting vertical gradient predictions with the gradient measurements. In our several previous studies, e.g., Jałocha et al (2010Jałocha et al ( , 2011, we modelled spiral galaxies in the approximation of an infinitesimally thin disk. In this framework, we could easily obtain high values of the vertical gradient of rotation, in accord with gradient measurements.…”

Section: Introductionmentioning

confidence: 99%

“…In our several previous studies, e.g., Jałocha et al (2010Jałocha et al ( , 2011, we modeled spiral galaxies in the approximation of an infinitesimally thin disk. In this framework, we easily obtained high values of the vertical gradient of rotation, in accord with gradient measurements.…”

Section: Introductionmentioning

confidence: 99%

Constraining the vertical structure of the Milky Way rotation by microlensing in a finite-width global disk model

Jałocha

Sikora²,

Bratek

et al. 2014

A&A

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We model the vertical structure of mass distribution of the Milky Way galaxy in the framework of a finite-width global disk model. Assuming only the Galactic rotation curve, we tested the predictions of the model inside the solar orbit for two measurable processes that are unrelated to each other: the gravitational microlensing that allows one to fix the disk width-scale by the best fit to measurements, and the vertical gradient of rotation modeled in the quasi-circular orbits approximation. The former is sensitive to the gravitating mass in compact objects, the latter to all kinds of gravitating matter. The analysis points to a small width-scale of the considered disks and an at-most insignificant contribution of non-baryonic dark matter in the solar circle. The predicted high vertical gradient values in the rotation are consistent with the gradient measurements.

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“…Yet, because galactic differential rotation probably decreases with distance from the midplane (e.g., Levine et al 2008;Marasco & Fraternali 2011;Jałocha et al 2011, and references therein), we expect field lines to become less tightly wound up, and hence to have a larger pitch angle, at higher altitudes. Note that this is just a qualitative argument, and one should not try to directly link the vertical variation of the pitch angle to that of the rotational velocity.…”

Section: Generalization To Z-dependent Pitch Anglesmentioning

confidence: 99%

Analytical models of X-shape magnetic fields in galactic halos

Ferrière

Terral

2014

A&A

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Context. External spiral galaxies seen edge-on exhibit X-shape magnetic fields in their halos. Whether the halo of our own Galaxy also hosts an X-shape magnetic field is still an open question. Aims. We would like to provide the necessary analytical tools to test the hypothesis of an X-shape magnetic field in the Galactic halo. Methods. We propose a general method to derive analytical models of divergence-free magnetic fields whose field lines are assigned a specific shape. We then utilize our method to obtain four particular models of X-shape magnetic fields in galactic halos. In passing, we also derive two particular models of predominantly horizontal magnetic fields in galactic disks. All our field models have spiraling field lines with spatially varying pitch angle. Results. Our four halo field models do indeed lead to X patterns in synthetic synchrotron polarization maps. Their precise topologies can all be explained by the action of a wind blowing outward from the galactic disk or from the galactic center. In practice, our field models may be used for fitting purposes or as inputs to various theoretical problems.

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Vertical gradients of azimuthal velocity in a global thin-disc model of spiral galaxies NGC 2403, NGC 4559, NGC 4302 and NGC 5775

Cited by 6 publications

References 11 publications

The role of large-scale magnetic fields in galaxy NGC 891: can magnetic fields help to reduce the local mass-to-light ratio in the galactic outskirts?

The role of large-scale magnetic fields in galaxy NGC 891: can magnetic fields help to reduce the local mass-to-light ratio in the galactic outskirts?

Constraining the vertical structure of the Milky Way rotation by microlensing in a finite-width global disk model

Analytical models of X-shape magnetic fields in galactic halos

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