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Breaking the mass / anisotropy degeneracy in the Coma cluster | | Gary A. Mamon
; Ewa L. Lokas & Teresa Sanchis
; | | Date: |
21 Apr 2004 | | Journal: | IAU Colloq. 195 (Cambridge Univ. Press), p. 413 (2004) DOI: 10.1017/S1743921304000869 | | Subject: | astro-ph | | Affiliation: | IAP, Paris, France, Copernicus Center, Warsaw, Poland, Dep. di Astronomia i Meteorologia, Univ. de Barcelona, Spain | | Abstract: | We provide the first direct lifting of the mass/anisotropy degeneracy for a cluster of galaxies, by jointly fitting the line of sight velocity dispersion and kurtosis profiles of the Coma cluster, assuming an NFW tracer density profile, a generalized-NFW dark matter profile and a constant anisotropy profile. We find that the orbits in Coma must be quasi-isotropic, and find a mass consistent with previous analyses, but a concentration parameter 50% higher than expected in cosmological N-body simulations. We then test the accuracy of our method on realistic non-spherical systems with substructure and streaming motions, by applying it to the ten most massive structures in a cosmological N-body simulation. We find that our method yields fairly accurate results on average (within 20%), although with a wide variation (factor 1.7 at 1 sigma) for the concentration parameter, with decreased accuracy and efficiency when the projected mean velocity is not constant with radius. | | Source: | arXiv, astro-ph/0404415 | | Services: | Forum | Review | PDF | Favorites | |
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