ﻻ يوجد ملخص باللغة العربية
[Abridged] XMMU J2235.3-2557 is one of the most distant X-ray selected clusters, spectroscopically confirmed at z=1.39. We characterize the galaxy populations of passive members, the thermodynamical properties of the hot gas, its metal abundance and the total mass of the system using imaging data with HST/ACS (i775 and z850 bands) and VLT/ISAAC (J and K_s bands), extensive spectroscopic data obtained with VLT/FORS2, and deep Chandra observations. Out of a total sample of 34 spectroscopically confirmed cluster members, we selected 16 passive galaxies within the central 2 (or 1 Mpc) with ACS coverage, and inferred star formation histories for a sub-sample of galaxies inside and outside the core by modeling their spectro-photometric data with spectral synthesis models, finding a strong mean age radial gradient. Chandra data show a regular elongated morphology, closely resembling the distribution of core galaxies, with a significant cool core. We measure a global X-ray temperature of kT=8.6(-1.2,+1.3) keV (68% c.l.). By detecting the rest-frame 6.7 keV Iron K line, we measure a metallicty Z= 0.26(+0.20,-0.16) Zsun. In the likely hypothesis of hydrostatic equilibrium, we obtain a total mass of Mtot(<1 Mpc)=(5.9+-1.3)10^14 Msun. Overall, our analysis implies that XMM2235 is the hottest and most massive bona-fide cluster discovered to date at z>1, with a baryonic content, both its galaxy population and intra-cluster gas, in a significantly advanced evolutionary stage at 1/3 of the current age of the Universe.
Star-formation in the galaxy populations of local massive clusters is reduced with respect to field galaxies, and tends to be suppressed in the core region. Indications of a reversal of the star-formation--density relation have been observed in a few
We present a multi-wavelength study of galaxy populations in the core of the massive, X-ray luminous cluster XMMU J2235 at z=1.39, based on VLT and HST optical and near-infrared photometry. Luminosity functions in the z, H, and Ks bands show a faint-
We present a weak-lensing analysis of the z=1.4 galaxy cluster XMMU J2235.3-2557, based on deep Advanced Camera for Surveys images. Despite the observational challenge set by the high redshift of the lens, we detect a substantial lensing signal at th
We use HAWK-I, the recently-commissioned near-IR imager on Yepun (VLT-UT4), to obtain wide-field, high-resolution images of the X-ray luminous galaxy cluster XMMU J2235.3-2557 in the J and Ks bands, and we use these images to build a colour-magnitude
We took spatially resolved slit FORS2 spectra of 19 cluster galaxies at z=1.4, and 8 additional field galaxies at 1<z<1.2 using the ESO Very Large Telescope. The targets were selected from previous spectroscopic and photometric campaigns. Our spectro