In this second paper on the entire virial region of the relaxed fossil cluster RXJ 1159+5531 we present a hydrostatic analysis of the azimuthally averaged hot intracluster medium ( ICM ) using the results of Paper 1 ( ) .
For a model consisting of ICM , stellar mass from the central galaxy ( BCG ) , and an NFW dark matter ( DM ) halo , we obtain a good description of the projected radial profiles of ICM emissivity and temperature that yield precise constraints on the total mass profile .
The BCG stellar mass component is clearly detected with a K -band stellar mass-to-light ratio , M _ { \star } / L _ { K } = 0.61 \pm 0.11 M _ { \odot } / L _ { \odot } , consistent with stellar population synthesis models for a Milky-Way IMF .
We obtain a halo concentration , c _ { 200 } = 8.4 \pm 1.0 , and virial mass , M _ { 200 } = ( 7.9 \pm 0.6 ) \times 10 ^ { 13 } M _ { \odot } .
For its mass , the inferred concentration is larger than most relaxed halos produced in cosmological simulations with Planck parameters , consistent with RXJ 1159+5531 forming earlier than the general halo population .
The baryon fraction at r _ { 200 } , f _ { b, 200 } = 0.134 \pm 0.007 , is slightly below the Planck value ( 0.155 ) for the universe .
However , when we take into account the additional stellar baryons associated with non-central galaxies and the uncertain intracluster light ( ICL ) , f _ { b, 200 } increases by \approx 0.015 , consistent with the cosmic value and therefore no significant baryon loss from the system .
The total mass profile is nearly a power law over a large radial range ( \sim 0.2 -10 R _ { e } ) , where the corresponding density slope \alpha obeys the \alpha - R _ { e } scaling relation for massive early-type galaxies .
Performing our analysis in the context of MOND still requires a large DM fraction ( 85.0 \% \pm 2.5 \% at r = 100 kpc ) similar to that obtained using the standard Newtonian approach .
The detection of a plausible stellar BCG mass component distinct from the NFW DM halo in the total gravitational potential suggests that \sim 10 ^ { 14 } M _ { \odot } represents the mass scale above which dissipation is unimportant in the formation of the central regions of galaxy clusters .