Discovery of an Overlapping Cluster in Abell 1674 Field with Suzaku
  We present the results of a Suzaku observation of Abell 1674, an optically
very rich (richness class 3) cluster cataloged as z = 0.1066. We discover the
He-like Fe K-shell line from the central region for the first time, and find
that the X-ray spectrum yields a high redshift of 0.215^{+0.007}_{-0.006}. On
the other hand, the spectrum of the southwestern region is fitted with a
redshift of 0.11 \pm 0.02 by the He-like Fe L-shell lines, consistent with the
optically determined value. The gas temperature, metal abundance, and core
radius of the X-ray emission in the central region are 3.8 \pm 0.2 keV, 0.20
\pm 0.05 Z_solar and 450 \pm 40 kpc, respectively, while those in the
southwestern region are 2.0 \pm 0.2 keV, 0.41^{+0.17}_{-0.13} Z_solar and
220^{+90}_{-70} kpc, respectively. These parameters are typical for clusters.
We thus conclude that Abell 1674 consists of two independent clusters, A1674-C
at z ~0.22 and A1674-SW at z ~0.11, overlapping along the line of sight. The
X-ray luminosities of A1674-C within r = 2 Mpc is 15.9 \pm 0.6 \times 10^{43}
erg s^{-1} in the 0.1-2.4 keV energy band, while that for A1674-SW is 1.25 \pm
0.07 \times 10^{43} erg s^{-1}. Both are consistent with those expected from
the L-T relation of clusters within a factor of 2. This is another support for
our conclusion.
