We present the combined analysis of the metal content of 83 objects in the redshift range 0.09-1.39, and spatially-resolved in the 3 bins (0-0.15, 0.15-0.4, >0.4) R500, as obtained with similar analysis using XMM-Newton data in Leccardi & Molendi (2008) and Baldi et al. (2012). We use the pseudo-entropy ratio to separate the Cool-Core (CC) cluster population, where the central gas density tends to be relatively higher, cooler and more metal rich, from the Non-Cool-Core systems. The average, redshift-independent, metal abundance measured in the 3 radial bins decrease moving outwards, with a mean metallicity in the core that is even 3 (two) times higher than the value of 0.16 times the solar abundance in Anders & Grevesse (1989) estimated at r>0.4 R500 in CC (NCC) objects. We find that the values of the emission-weighted metallicity are well-fitted by the relation $Z(z) = Z_0 (1+z)^{-gamma}$ at given radius. A significant scatter, intrinsic to the observed distribution and of the order of 0.05-0.15, is observed below 0.4 R500. The nominal best-fit value of $gamma$ is significantly different from zero in the inner cluster regions ($gamma = 1.6 pm 0.2$) and in CC clusters only. These results are confirmed also with a bootstrap analysis, which provides a still significant negative evolution in the core of CC systems (P>99.9 per cent). No redshift-evolution is observed when regions above the core (r > 0.15 R500) are considered. A reasonable good fit of both the radial and redshift dependence is provided from the functional form $Z(r,z)=Z_0 (1+(r/0.15 R500)^2)^{-beta} (1+z)^{-gamma}$, with $(Z_0, beta, gamma) = (0.83 pm 0.13, 0.55 pm 0.07, 1.7 pm 0.6)$ in CC clusters and $(0.39 pm 0.04, 0.37 pm 0.15, 0.5 pm 0.5)$ for NCC systems. Our results represent the most extensive study of the spatially-resolved metal distribution in the cluster plasma as function of redshift.
In the effort to understand the link between the structure of galaxy clusters and their galaxy populations, we focus on MACSJ1206.2-0847 at z~0.44 and probe its substructure in the projected phase space through the spectrophotometric properties of a large number of galaxies from the CLASH-VLT survey. Our analysis is mainly based on an extensive spectroscopic dataset of 445 member galaxies, mostly acquired with VIMOS@VLT as part of our ESO Large Programme, sampling the cluster out to a radius ~2R200 (4 Mpc). We classify 412 galaxies as passive, with strong Hdelta absorption (red and blue galaxies, and with emission lines from weak to very strong. A number of tests for substructure detection are applied to analyze the galaxy distribution in the velocity space, in 2D space, and in 3D projected phase-space. Studied in its entirety, the cluster appears as a large-scale relaxed system with a few secondary, minor overdensities in 2D distribution. We detect no velocity gradients or evidence of deviations in local mean velocities. The main feature is the WNW-ESE elongation. The analysis of galaxy populations per spectral class highlights a more complex scenario. The passive galaxies and red strong Hdelta galaxies trace the cluster center and the WNW-ESE elongated structure. The red strong Hdelta galaxies also mark a secondary, dense peak ~2 Mpc at ESE. The emission line galaxies cluster in several loose structures, mostly outside R200. The observational scenario agrees with MACS J1206.2-0847 having WNW-ESE as the direction of the main cluster accretion, traced by passive galaxies and red strong Hdelta galaxies. The red strong Hdelta galaxies, interpreted as poststarburst galaxies, date a likely important event 1-2 Gyr before the epoch of observation. The emission line galaxies trace a secondary, ongoing infall where groups are accreted along several directions.
We present VIsible Multi-Object Spectrograph (VIMOS) observations of a z 6 galaxy quintuply imaged by the Frontier Fields galaxy cluster RXC J2248.7-4431 (z=0.348). This sub-L^*, high-z galaxy has been recently discovered by Monna et al. (2013) using dropout techniques with the 16-band HST photometry acquired as part of the Cluster Lensing And Supernova survey with Hubble (CLASH). Obtained as part of the CLASH-VLT survey, the VIMOS medium-resolution spectra of this source show a very faint continuum between ~8700A and ~9300A and a prominent emission line at 8643A, which can be readily identified with Lyman-alpha at z=6.110. The emission line exhibits an asymmetric profile, with a more pronounced red wing. The rest-frame equivalent width of the line is EW=79+-10A. After correcting for magnification, the star-formation rate (SFR) estimated from the Lya line is SFR(Lya)=11 M_{sol}/yr and that estimated from the UV data is SFR(UV)=3 M_{sol}/yr. We estimate that the effective radius of the source is R_e<~0.4 kpc, which implies a star formation surface mass density Sigma_{SFR}>6 M_{sol}/yr/kpc^2 and, using the Kennicutt-Schmidt relation, a gas surface mass density Sigma_{gas}>10^3 M_{sol}/pc^2. Our results support the idea that this magnified, distant galaxy is a young and compact object with 0.4 L^* at z=6, with comparable amount of mass in gas and stars. Future follow-up observations with ALMA will provide valuable insight into the SFR and molecular gas content of this source. In the spirit of the Frontier Fields initiative, we also publish the redshifts of several multiply imaged sources and other background objects which will help improving the strong lensing model of this galaxy cluster.
We use an unprecedented data-set of about 600 redshifts for cluster members, obtained as part of a VLT/VIMOS large programme, to constrain the mass profile of the z=0.44 cluster MACS J1206.2-0847 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. 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) 10^15 Msun 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. 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 [abridged]
