Journal Article

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

Joanna Jałocha, Łukasz Bratek, Marek Kutschera and Piotr Skindzier

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 412, issue 1, pages 331-336
Published in print March 2011 | ISSN: 0035-8711
Published online March 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17906.x
Vertical gradients of azimuthal velocity in a global thin-disc model of spiral galaxies NGC 2403, NGC 4559, NGC 4302 and NGC 5775

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We estimate the vertical gradient of rotational velocity for several spiral galaxies in the framework of a global thin-disc model, using the approximation of quasi-circular orbits. We obtain gradients having a broad range of values, in agreement with measurements, for galaxies with both low and high gradients. To model the gradient, it suffices to know the rotation curve only. We illustrate, using the example of galaxy NGC 4302 with particularly high gradients, that mass models of galactic rotation curves that assume a significant spheroidal mass component reduce the predicted gradient value, which may suggest that the mass distribution is dominated by a flattened disc-like component. We conclude that the value and behaviour of the vertical gradient in rotational velocity can be used to study the mass distribution in spiral galaxies.

Keywords: galaxies: kinematics and dynamics; galaxies: spiral; galaxies: structure

Journal Article.  3998 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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