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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 710706.0, MPI für Astronomie / Publikationen_mpia
Multiple pattern speeds in disc galaxies
Authors:Font, J.; Querejeta, M.; Beckman, J. E.; James, P.; Corsini, E. M.
Place of Publication:San Francisco
Date of Publication (YYYY-MM-DD):2014
Audience:Not Specified
Abstract / Description:We have used 2-dimensional velocity maps derived from Fabry-Perot data cubes, mapping the Halpha emission line from gas-rich nearby galaxies, to determine the resonance radii. This is done by subtracting off the rotation curve model from the initial velocity map yielding the residual velocity field, and finding the galactocentric radii at which these residual velocities change phase in the radial direction. A histogram of the number of pixels across which the phase changes take place shows a set of well defined peaks which give the resonance radii. We can then use the frequency curves, derived from the rotation curve, to identify which resonances are corotations. Some of these correspond to bars, others to other disk features. We find an interesting pattern in over 70% of the sample: given two pattern speeds, say Omega1 and Omega2, the outer Lindblad resonance of Omega1 coincides with the corotation of Omega2, and the inner 4:1 resonance of Omega2 coincides with the corotation of Omega1. We compute the ratio of corotation radius to bar length where we have good enough image quality, finding a mean value of 1.3, and a shallow increase towards later type galaxies. In double barred galaxies we find that the nuclear bar rotates 3.3-3.6 times faster than the main bar.
External Publication Status:published
Document Type:Other
Communicated by:N. N.
Affiliations:MPI für Astronomie
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