2001/06/21 by James S. Bullock · 4 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics #Cuspy halo problem #Dark matter #Dark matter halo #Galaxies: Formation, Evolution, Phenomena #Galaxy #Halo #Physics #Redshift #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.1142/9789812778017_0018
5 pages, 2 figures, to appear in proceedings of the May 2001 Yale workshop "The Shapes of Galaxies and their Halos"
arxiv created 2001/06/21 · openalex publication_date 2002/03/01 · arxiv updated 2017/08/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
I present an analysis of the density shapes of dark matter halos in LCDM and LWDM cosmologies. The main results are derived from a statistical sample of galaxy-mass halos drawn from a high resolution LCDM N-body simulation. Halo shapes show significant trends with mass and redshift: low-mass halos are rounder than high mass halos, and, for a fixed mass, halos are rounder at low z. Contrary to previous expectations, which were based on cluster-mass halos and non-COBE normalized simulations, LCDM galaxy-mass halos at z=0 are not strongly flattened, with short to long axis ratios of s = 0.70 +/- 0.17. I go on to study how the shapes of individual halos change when going from a LCDM simulation to a simulation with a warm dark matter power spectrum (LWDM). Four halos were compared, and, on average, the WDM halos are more spherical than their CDM counterparts (s =0.77 compared to s = 0.71). A larger sample of objects will be needed to test whether the trend is significant.