Astronomy and Astrophysics, volume 489, 981-988 (2008/10-3)
HAWK-I imaging of the X-ray luminous galaxy cluster XMMUJ2235.3-2557. The red sequence at z=1.39.
LIDMAN C., ROSATI P., TANAKA M., STRAZZULLO V., DEMARCO R., MULLIS C., AGEORGES N., KISSLER-PATIG M., PETR-GOTZENS M.G. and SELMAN F.
Abstract (from CDS):
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 diagram of cluster galaxies. Galaxies in the core of the cluster form a tight red sequence with a mean J-Ks colour of 1.9 (Vega system). The intrinsic scatter in the colour of galaxies that lie on the red sequence is similar to that measured for galaxies on the red sequence of the Coma cluster. The slope and location of the red sequence can be modelled by passively evolving the red sequence of the Coma cluster backwards in time. Using simple stellar population (SSP) models, we find that galaxies in the core of XMMU J2235.3-2557
are, even at z=1.39, already 3Gyr old, corresponding to a formation redshift of zf
∼4. Outside the core, the intrinsic scatter and the fraction of galaxies actively forming stars increase substantially. Using SSP models, we find that most of these galaxies will join the red sequence within 1.5Gyr. The contrast between galaxies in the cluster core and galaxies in the cluster outskirts indicates that the red sequence of XMMU J2235.3-2557
is being built from the dense cluster core outwards.
galaxies: clusters: general - galaxies: clusters: individual: XMMU J2235.3-2557 - galaxies: evolution
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