Kavli Affiliate: Eli S. Rykoff
| First 5 Authors: Yuanyuan Zhang, Yuanyuan Zhang, , ,
| Summary:
We investigate a splashback-like feature in the outer region of central
galaxies (CGs) in clusters. This feature is detected as a "dip" in the radial
slope of the CG surface brightness, derived through the stacking of Dark Energy
Survey data of over four thousand galaxy clusters in the redshift range of 0.2
to 0.5 with richness 20 and above. The local minimum of the dip occurs between
40 to 60 kpc from the CG center, with a mild dependence on cluster richness.
This feature resembles the density transition caused by the splashback effect
at the outskirts of galaxy clusters, when accreted matter reaches the apocenter
for the first time. We turn to the IllustrisTNG hydro-dynamic simulation to
gain theoretical insights. Density bumps, shells and accretion streaks are
identified in the diffuse stellar content of the CGs and intra-cluster light
which relate to the recent history of disruption and accretion. These features
occur at the outskirts of the CGs, up to several hundred kiloparsecs from the
cluster center. Thus, the location of the splashback-like dip in the data
potentially marks the edge of the CG and the beginning of a region with the
cluster diffuse light undergoing active or recent accretion.
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