Abstract / Description of output
We present new spectroscopic observations of the most distant
X-ray-selected galaxy cluster currently known, XMMXCS J2215.9-1738 at
z=1.457, obtained with the DEIMOS instrument at the W. M. Keck
Observatory and the FORS2 instrument on the ESO Very Large Telescope.
Within the cluster virial radius, as estimated from the cluster X-ray
properties, we increase the number of known spectroscopic cluster
members to 17 objects, and calculate the line-of-sight velocity
dispersion of the cluster to be 580+/-140 km s-1. We find
mild evidence that the velocity distribution of galaxies within the
virial radius deviates from a single Gaussian. We show that the
properties of J2215.9-1738 are inconsistent with self-similar evolution
of local X-ray scaling relations, finding that the cluster is
underluminous given its X-ray temperature, and that the intracluster
medium contains ~2-3 times the kinetic energy per unit mass of the
cluster galaxies. These results can perhaps be explained if the cluster
is observed in the aftermath of an off-axis merger. Alternatively,
heating of the intracluster medium through supernovae and/or active
galactic nucleus activity, as is required to explain the observed slope
of the local X-ray luminosity-temperature relation, may be responsible.
Original language | English |
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Pages (from-to) | 1000-1009 |
Journal | Astrophysical Journal |
Volume | 670 |
Publication status | Published - 1 Dec 2007 |
Keywords / Materials (for Non-textual outputs)
- galaxies: clusters: individual (XMMXCS J2215.9-1738)
- X-Rays: Galaxies: Clusters