Intracluster Light Properties in a Fossil Cluster at z=0.47
  Galaxy clusters contain a diffuse stellar component outside the cluster's
galaxies, which is observed as faint intracluster light (ICL). Using
Gemini/GMOS-N deep imaging and multi-object spectroscopy of a massive fossil
cluster at a redshift of $z=0.47$, RX J105453.3+552102 (J1054), we improve the
observational constraints on the formation mechanism of the ICL. We extract the
ICL surface brightness and colour profiles out to 155 kpc from the brightest
cluster galaxy (BCG) with a detection limit of 28.7 mag/arcsec$^2$ (1$\sigma$,
4.8" x 4.8"; i-band). The colour of the diffuse light is similar to that of the
BCG and central bright galaxies out to $\sim$ 70 kpc, becoming slightly bluer
toward the outside. We find that the ICL distribution shows better agreement
with the spatial distribution of member galaxies than with the BCG-dominated
cluster luminosity distribution. We report the ICL fraction of J1054 as $15.07
\pm 4.57 \%$ in the range of $60 \sim 155$ kpc from the BCG, which appears to
be higher than the ICL fraction-redshift trend in previous studies. Our
findings suggest that intracluster stars seems not to be explained by one
dominant production mechanism. However, a significant fraction of the ICL of
J1054 may have been generated from the outskirts of infalling/satellite
galaxies more recently rather than by the BCG at the early stage of the
cluster.
