Research Center for Astronomy

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Tuesday 27 February 2018 @ 12:00

The manifold theory and its application in barred spiral galaxies

Mirella Harsoula
Research Center for Astronomy and Applied Mathematics of the Academy of Athens


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Featured Picture

 

The picture shows the applicability of the manifold theory of spiral arms in N-body simulations of barred-spiral galaxies. The red and blue points visualize the `apocentric' unstable manifolds emanating from periodic orbits in the neighborhood of the bar's Lagrangian points L1 and L2. These manifolds support `chaotic spirals' (Patsis 2006) in the form of outflows from the region of L1 or L2. The dark contour lines produce the image of the disc in the N-body simulation using the Sobel-Feldman edge detection algorithm for recognizing spiral or ring patterns in the disc. According to the manifold theory, the complexity of these patterns is related to the complexity of the `homoclinic lobes' formed by the invariant manifolds. The simulation was performed using a new N-body code based on a Cartesian grid solver of Poisson's equation using fast pre-conditioning techniques (Kyziropoulos et al. 2016, 2017). The invariant manifold theory is one of the main current theories for modeling spirals beyond the ends of bars (see Dobbs & Baba 2014). It has been developed in two versions: the `apocentric' manifolds (Voglis et al 2006) and the `flux tube manifolds' (Romero-Gomez et al. 2006, 2007), see Athanassoula (2012) and Efthymiopoulos (2010) for reviews and further references.

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