Discovery of the X-ray selected galaxy cluster XMMU J0338.8+0021 at z =
  1.49 - Indications for a young system with a forming brightest galaxy
  We report on the discovery of a galaxy cluster at z = 1.490 originally
selected as an extended X-ray source in the XMM-Newton Distant Cluster Project.
Further observations carried out with the VLT-FORS2 spectrograph allowed the
spectroscopic confirmation of seven secure cluster members, providing a median
system redshift of z = 1.490 +/- 0.009. The color magnitude diagram of XMMU
J0338.8+0021 reveals the presence of a well populated red sequence with z-H ~
3, albeit with an apparent significant scatter in color. Since we do not detect
indications for strong star formation activity in any of the objects, the color
spread could indicate different stellar ages of the member galaxies. In
addition, we found the brightest cluster galaxy in a very active dynamical
state, with an interacting, merging companion located at a physical projected
distance of d ~ 20kpc. From the X-ray luminosity we estimate a cluster mass of
M200 ~ 1.2 x 10^(14) Msun. The data seem to suggest a scenario in which XMMU
J0338.8+0021 is a young system, possibly caught in a moment of active ongoing
mass assembly.
