Issue |
A&A
Volume 439, Number 1, August III 2005
|
|
---|---|---|
Page(s) | 29 - 33 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20042112 | |
Published online | 22 July 2005 |
Galaxy populations of double cluster RX J1053.7+5735 at z = 1.13
1
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 85748 Garching, Germany e-mail: hashimot@mpe.mpg.de
2
Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, USA
3
Palomar Observatory, California Institute of Technology, MS 320-47 Pasadena, CA 91125, USA
Received:
4
October
2004
Accepted:
23
February
2005
We present a study of the galaxy population in the cluster RX J1053.7+5735,
one of the most distant
X-ray selected clusters of galaxies and one which also shows an unusual
double-lobed X-ray morphology,
indicative of a possible equal-mass cluster merger.
The cluster was discovered during
the ROSAT deep pointings in the direction of the Lockman Hole.
Using Keck-DEIMOS
spectroscopic observations of galaxies
in the 20
1
5 region surrounding
RX J1053.7+5735, we
secured redshifts for six
galaxies
in the range
, with a mean redshift
.
This mean redshift agrees well with the
cluster X-ray redshift previously estimated
from
the cluster X-ray Fe-K line,
confirming the presence of a cluster at
.
Galaxies with concordant redshifts
are located in both eastern and western sub-clusters of
the double cluster structure,
which indicates that
both sub-clusters are at similar redshifts.
This result is also consistent with a previous
claim that both eastern and western X-ray lobes
have similar X-ray redshifts.
Based on their
separation of ~250 kpc,
these results support the interpretation that
RX J1053.7+5735 is an equal-mass cluster merger taken
place at
, although
further direct evidence for a dynamical state of the cluster is
needed to make a more definitive statement about
the cluster merging state.
The six galaxies have a line-of-sight velocity
dispersion
~ 650 km s-1,
and
all six show clear absorption features of CaII H and K and
several Balmer lines that are typical of early galaxies at the present
epoch, in agreement with their
colors.
A color–magnitude diagram, constructed from
deep optical/NIR observations of the RX J1053.7+5735 field,
shows a clear red color sequence.
There is an indication that the red sequence
in RX J1053.7+5735 lies ~0.3 to the blue of the Coma line,
qualitatively consistent with previous studies investigating
other clusters at
.
Key words: galaxies: clusters: general / galaxies: high-redshift / infrared: galaxies / X-rays: galaxies: clusters / galaxies: evolution / galaxies: stellar content
© ESO, 2005
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