A Method for Reconstructing the Full Vector Velocity Field
in the Gaseous Disks of Spiral Galaxies

V. V. Lyakhovich, A. M. Fridman, O. V. Khoruzhii, and A. I. Pavlov

Institute of Astronomy, Russian Academy of Sciences, ul. Pyatnitskaya 48, Moscow, 109017 Russia

Received March 3, 1996

Abstract—A method is proposed for reconstructing the full vector velocity field (i.e., the three velocity components) in the gaseous disks of spiral galaxies from observed radial velocities. The method is based on Fourier analysis of the observed velocity field and interpretation of the resulting Fourier harmonics in the framework of a model accounting for motion in the spiral arms. The model is based on the concept of galactic spirals as density waves. The proposed method can be used to (1) find noncircular velocities associated with spiral-vortex structure; (2) find fundamental parameters for this structure, such as the angular rotational velocity, the corotation radius, and the location of giant anticyclones; (3) refine the rotation curves of galaxies by taking into account noncircular velocities in spiral density waves, which leads to a more precise determination of the mass distribution in the galaxies; and (4) refine parameters determining the galactic plane: inclination angle, location of the center of rotation, and the position angle of the major dynamical axis of the galaxy. Knowledge of the velocity field in spiral galaxies makes it possible to better understand galactic structures and mechanisms for their formation.

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