The buildup of the intracluster light of Abell 85 as seen by Subaru's Hyper Suprime-Cam

The study of low surface brightness light in large, deep imaging surveys is still uncharted territory as automated data reduction pipelines over-subtract or eliminate this light. Using archival data of the Abell 85 cluster of galaxies taken with Hyper Suprime-Cam on the Subaru Telescope, we show that using careful data processing can unveil the diffuse light within the cluster, the intracluster light. We reach surface brightness limits of $\mu_{g}^{limit}$(3$\sigma$, 10"x10") = 30.9 mag/arcsec$^2$, and $\mu_{i}^{limit}$(3$\sigma$, 10"x10") = 29.7 mag/arcsec$^2$. We measured the radial surface brightness profiles of the brightest cluster galaxy out to the intracluster light (radius $\sim215$ kpc), for the g and i bands. We found that both the surface brightness and the color profiles become shallower beyond $\sim75$ kpc suggesting that a distinct component, the intracluster light, starts to dominate at that radius. The color of the profile at $\sim100$ kpc suggests that the buildup of the intracluster light of Abell 85 occurs by the stripping of massive ($\sim10^{10}M_{\odot}$) satellites. The measured fraction of this light ranges from 8% to 30% in g, depending on the definition of intracluster light chosen.