Density profiles of dark matter halos with anisotropic velocity tensors |
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Authors: | N Hiotelis |
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Institution: | 1st Experimental Lyceum of Athens, Ipitou 15, Plaka, 10557, Athens, Greece, |
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Abstract: | We present density profiles, that are solutions of the spherical Jeans equation, derived under the following two assumptions: (i) the coarse grained phase-density follows a power-law of radius, ρ/σ3 ∝ r? , and (ii) the velocity anisotropy parameter is given by the relation βa(r)=β1+2β2 (r/r*)/1+(r/r*)2] where β1, β2 are parameters and r* equals twice the virial radius, rvir, of the system. These assumptions are well motivated by the results of N-body simulations. Density profiles have increasing logarithmic slopes γ, defined by γ=?d ln ρ/d ln r. The values of γ at r=10?2.5rvir, a distance where the systems could be resolved by large N-body simulations, lie in the range 1.0–1.6. These inner values of γ increase for increasing β1 and for increasing concentration of the system. On the other hand, slopes at r=rvir lie in the range 2.42–3.82. A model density profile that fits well the results at radial distances between 10?3rvir and rvir and connects kinematic and structural characteristics of spherical systems is described. |
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Keywords: | Galaxies: formation Galaxies: halos Galaxies: structure Methods: numerical Methods: analytical Dark matter |
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