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Detection of Intracluster Globular Clusters in the First JWST Images of the Gravitational Lens Cluster SMACS J0723.3-7327 at z = 0.39
We present a survey of globular clusters (GCs) in the massive gravitational
lens cluster SMACS J0723.3-7327 at based on the early released
JWST/NIRCam images. In the color-magnitude diagrams of the point sources we
find clearly a rich population of intracluster GCs that spread in a wide area
of the cluster. Their ages, considering the cluster redshift, are younger than
9.5 Gyr. The F200W (AB) magnitudes of these GCs, mag,
correspond to mag, showing that they belong to the
brightest GCs (including ultracompact dwarfs). The spatial distributions of
these GCs show a megaparsec-scale structure elongated along the major axis of
the brightest cluster galaxy. In addition, they show a large number of
substructures, some of which are consistent with the substructures seen in the
map of diffuse intracluster light. The GC number density map is, in general,
consistent with the dark matter mass density map based on the strong lensing
analysis in the literature. The radial number density profile of the GCs in the
outer region is steeper than the dark matter mass profile obtained from lensing
models. These results are consistent with those for the GCs found in the deep
HST images of Abell 2744, another massive cluster at , and in
simulated galaxy clusters. This shows that the intracluster GCs are an
excellent independent tool to probe the dark matter distribution in galaxy
clusters as well as to reveal the cluster assembly history in the JWST era.Comment: 25 pages, 12 figures, Accepted for publication in ApJ
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