Boxy/Peanut/X Bulges, Barlenses and the Thick Part of Galactic Bars: What Are They and How Did They Form?
Bars have a complex three-dimensional shape. In particular their inner part is vertically much thicker than the parts further out. Viewed edge-on, the thick part of the bar is what is commonly known as a boxy-, peanut-, or X- bulge and viewed face-on it is referred to as a barlens. These components are due to disc and bar instabilities and are composed of disc material. I review here their formation, evolution and dynamics, using simulations, orbital structure theory and comparisons to observations.
KeywordsPeriodic Orbit Orbital Structure Disc Galaxy Thick Part Unstable Periodic Orbit
I thank Albert Bosma for many stimulating discussions and the editors for inviting me to write this review. Figures 14.4 and 14.5 were made using glnemo2 (http://projets.lam.fr/-projects/glnemo2). I acknowledge financial support from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme FP7/2007-2013/ under REA grant agreement number PITN-GA-2011-289313 to the DAGAL network. I also acknowledge financial support from the CNES (Center National d’Etudes Spatiales – France) and from the “Programme National de Cosmologie et Galaxies” (PNCG) of CNRS/INSU, France, and HPC resources from GENCI- TGCC/CINES (Grants x2013047098 and x2014047098) and from the Mesocentre of Aix-Marseille Université (program DIFOMER).
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