Journal Article

A novel method to bracket the corotation radius in galaxy discs: vertex deviation maps

Santi Roca-Fàbrega, Teresa Antoja, Francesca Figueras, Octavio Valenzuela, Mercè Romero-Gómez and Bárbara Pichardo

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 440, issue 3, pages 1950-1963
ISSN: 0035-8711
Published online April 2014 | e-ISSN: 1365-2966 | DOI: https://dx.doi.org/10.1093/mnras/stu437
A novel method to bracket the corotation radius in galaxy discs: vertex deviation maps

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We map the kinematics of stars in simulated galaxy discs with spiral arms using the velocity ellipsoid vertex deviation ([math]). We use test particle simulations, and for the first time, fully self-consistent high-resolution N-body models. We compare our maps with the tight winding approximation model analytical predictions. We see that for all barred models, spiral arms rotate closely to a rigid body manner and the vertex deviation values correlate with the density peak's position bounded by overdense and underdense regions. In such cases, vertex deviation sign changes from negative to positive when crossing the spiral arms in the direction of disc rotation, in regions where the spiral arms are in between corotation radius (CR) and the Outer Lindblad Resonance (OLR). By contrast, when the arm sections are inside the CR and outside the OLR, [math] changes from negative to positive. We propose that measurements of the vertex deviation's pattern can be used to trace the position of the main resonances of the spiral arms. We propose that this technique might exploit future data from Gaia and APO Galactic Evolution Experiment (APOGEE) surveys. For unbarred N-body simulations with spiral arms corotating with disc material at all radii, our analysis suggests that no clear correlation exists between [math] and density structures.

Keywords: methods: analytical; methods: numerical; galaxies: kinematics and dynamics; galaxies: structure

Journal Article.  9539 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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