2012EPJWC..1901009V
The shape of dark matter haloes in the Aquarius simulations: Evolution and memory
Vera-Ciro, C. A. ( Kapteyn Astronomical Institute, Univ. of Groningen, P.O. Box 800, 9700 AV, Groningen, The Netherlands; ); Sales, L. V. ( Kapteyn Astronomical Institute, Univ. of Groningen, P.O. Box 800, 9700 AV, Groningen, The Netherlands; Max-Plank-Institut für Astrophysik, Karl-Schwarzschild-Straße, 1, 85740, Garching bei München, Germany ); Helmi, A. ( Kapteyn Astronomical Institute, Univ. of Groningen, P.O. Box 800, 9700 AV, Groningen, The Netherlands ) show affiliations
Assembling the Puzzle of the Milky Way, Le Grand-Bornand, France, Edited by C. Reylé; A. Robin; M. Schultheis; EPJ Web of Conferences, Volume 19, id.01009
Published in Feb 2012
We use the high resolution cosmological N-body simulations from the Aquarius project to investigate in detail the mechanisms that determine the shape of Milky Way-type dark matter haloes. We find that, when measured at the instantaneous virial radius, the shape of individual haloes changes with time, evolving from a typically prolate configuration at early stages to a more triaxial/oblate geometry at the present day. This evolution in halo shape correlates well with the distribution of the infalling material: prolate configurations arise when haloes are fed through narrow filaments, which characterizes the early epochs of halo assembly, whereas triaxial/oblate configurations result as the accretion turns more isotropic at later times. Interestingly, at redshift z = 0, clear imprints of the past history of each halo are recorded in their shapes at different radii, which also exhibit a variation from prolate in the inner regions to triaxial/oblate in the outskirts. Provided that the Aquarius haloes are fair representatives of Milky Way-like 1012M objects, we conclude that the shape of such dark matter haloes is a complex, time-dependent property, with each radial shell retaining memory of the conditions at the time of collapse.
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