CLASH-VLT: The mass, velocity-anisotropy, and pseudo-phase-space density profiles of the z = 0.44 galaxy cluster MACS J1206.2-0847
Résumé
Aims. We constrain the mass, velocity-anisotropy, and pseudo-phase-space
density profiles of the z = 0.44 CLASH cluster MACS J1206.2-0847, using the projected phase-space
distribution of cluster galaxies in combination with gravitational lensing.Methods. We use an unprecedented data-set of ≃600 redshifts for cluster
members, obtained as part of a VLT/VIMOS large program, to constrain the cluster mass
profile over the radial range ~0–5 Mpc (0–2.5 virial radii) using the MAMPOSSt and Caustic
methods. We then add external constraints from our previous gravitational lensing
analysis. We invert the Jeans equation to obtain the velocity-anisotropy profiles of
cluster members. With the mass-density and velocity-anisotropy profiles we then obtain the
first determination of a cluster pseudo-phase-space density profile.Results. The kinematics and lensing determinations of the cluster mass
profile are in excellent agreement. This is very well fitted by a NFW model with mass
M200 = (1.4 ± 0.2) × 1015 M⊙
and concentration c200 = 6 ± 1, only slightly higher than
theoretical expectations. Other mass profile models also provide acceptable fits to our
data, of (slightly) lower (Burkert, Hernquist, and Softened Isothermal Sphere) or
comparable (Einasto) quality than NFW. The velocity anisotropy profiles of the passive and
star-forming cluster members are similar, close to isotropic near the center and
increasingly radial outside. Passive cluster members follow extremely well the theoretical
expectations for the pseudo-phase-space density profile and the relation between the slope
of the mass-density profile and the velocity anisotropy. Star-forming cluster members show
marginal deviations from theoretical expectations.Conclusions. This is the most accurate determination of a cluster mass
profile out to a radius of 5 Mpc, and the only determination of the velocity-anisotropy
and pseudo-phase-space density profiles of both passive and star-forming galaxies for an
individual cluster. These profiles provide constraints on the dynamical history of the
cluster and its galaxies. Prospects for extending this analysis to a larger cluster sample
are discussed.
| Origine | Publication financée par une institution |
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