2012/05/31 by Martin Sparre, Steen H. Hansen, Steen H Hansen · 13 citations
Engineering · Physics and Astronomy · #Accretion (finance) #Anisotropy #Astronomy and Astrophysical Research #Collision #Cosmological constant #Cosmology #Dark matter #Galaxies: Formation, Evolution, Phenomena #Gravitation #Halo #Peculiar velocity #Space Technology and Applications #astro-ph.CO
paper · pdf · doi:10.1088/1475-7516/2012/07/042
published in Journal of Cosmology and Astroparticle Physics 2012(07), 042 (Institute of Physics) · 19 pages, 15 figures, Resubmitted to JCAP after referee comments
arxiv created 2012/06/28 · openalex publication_date 2012/07/23 · arxiv updated 2012/07/26 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Dark matter haloes in cosmological N-body simulations are affected by processes such as mergers, accretion and the gravitational interaction with baryonic matter. Typically the analysis of dark matter haloes is performed in spherical or elliptical bins and the velocity distributions are often assumed to be constant within those bins. However, the velocity anisotropy, which describes differences between the radial and tangential velocity dispersion, has recently been show to have a strong dependence on direction in the triaxial halos formed in cosmological simulations. In this study we derive properties of particles in cones parallel or perpendicular to the collision axis of merger remnants. We find that the velocity anisotropy has a strong dependence on direction. The finding that the direction-dependence of the velocity anisotropy of a halo depends on the merger history, explains the existence of such trends in cosmological simulations. It also explains why a large diversity is seen in the velocity anisotropy profiles in the outer parts of high-resolution simulations of cosmological haloes.