Is diffuse intracluster light a good tracer of the galaxy cluster matter
  distribution?
  We explore the relation between diffuse intracluster light (central galaxy
included) and the galaxy cluster (baryonic and dark) matter distribution using
a sample of 528 clusters at $0.2\leq z \leq 0.35$ found in the Dark Energy
Survey (DES) Year 1 data. The surface brightness of the diffuse light shows an
increasing dependence on cluster total mass at larger radius, and appears to be
self-similar with a universal radial dependence after scaling by cluster
radius. We also compare the diffuse light radial profiles to the cluster
(baryonic and dark) matter distribution measured through weak lensing and find
them to be comparable. The IllustrisTNG galaxy formation simulation, TNG300,
offers further insight into the connection between diffuse stellar mass and
cluster matter distributions -- the simulation radial profile of the diffuse
stellar component does not have a similar slope with the total cluster matter
content, although that of the cluster satellite galaxies does. Regardless of
the radial trends, the amount of diffuse stellar mass has a low-scatter scaling
relation with cluster's total mass in the simulation, out-performing the total
stellar mass of cluster satellite galaxies. We conclude that there is no
consistent evidence yet on whether or not diffuse light is a faithful radial
tracer of the cluster matter distribution. Nevertheless, both observational and
simulation results reveal that diffuse light is an excellent indicator of the
cluster's total mass.
