ar X iv : a st ro - p h / 01 06 38 0 v 1 2 1 Ju n 20 01 SHAPES OF DARK MATTER HALOS
نویسنده
چکیده
I present an analysis of the density shapes of dark matter halos in ΛCDM and ΛWDM cosmologies. The main results are derived from a statistical sample of galaxy-mass halos drawn from a high resolution ΛCDM 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, ΛCDM 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 ΛCDM simulation to a simulation with a warm dark matter power spectrum (ΛWDM). 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.
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