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Breaking the mass/anisotropy degeneracy in the Coma cluster

Published online by Cambridge University Press:  06 October 2004

Gary A. Mamon
Affiliation:
IAP, Paris, France email: gam@iap.fr
Ewa L. Łokas
Affiliation:
Copernicus Center, Warsaw, Poland email: lokas@camk.edu.pl
Teresa Sanchis
Affiliation:
Dep. di Astronomia i Meteorologia, Univ. de Barcelona, Spain email: tsanchis@am.ub.es
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Abstract

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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.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Type
Contributed Papers
Copyright
© 2004 International Astronomical Union