Issue |
A&A
Volume 489, Number 3, October III 2008
|
|
---|---|---|
Page(s) | 981 - 988 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:200810528 | |
Published online | 08 August 2008 |
HAWK-I imaging of the X-ray luminous galaxy cluster XMMU J2235.3-2557*
The red sequence at z = 1.39
1
European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Santiago, Chile e-mail: clidman@eso.org
2
European Southern Observatory, Karl-schwarzschild-Strasse 2, 85748 Garching, Germany
3
National Radio Astronomy Observatory, PO Box O, Socorro, NM 87801, USA
4
Department of Physics and Astronomy, John Hopkins University, Baltimore, USA
5
Wachovia Corporation, NC6740, 100 N. Main Street, Winston-Salem, NC 27101, USA
6
MPI für extraterrestische Physik, Giessenbachsrtasse, 85748 Garching, Germany
Received:
5
July
2008
Accepted:
31
July
2008
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
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
, already 3 Gyr
old, corresponding to a formation redshift of
. 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 1.5 Gyr. 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.
Key words: galaxies: clusters: general / galaxies: clusters: individual: XMMU J2235.3-2557 / galaxies: evolution
© ESO, 2008
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