The Buildup of the Intracluster Light of A85 as Seen by Subaru’s Hyper Suprime-Cam

Abstract

Abstract 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 A85 cluster of galaxies taken with the 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 (3σ, 10″ × 10″) = 30.9 and (3σ, 10″ × 10″) = 29.7 mag arcsec−2. We measured the radial surface brightness profiles of the brightest cluster galaxy out to the intracluster light (radius ∼215 kpc) for the g and i bands. We found that both the surface brightness and the color profiles become shallower beyond ∼75 kpc suggesting that a distinct component, the intracluster light, starts to dominate at that radius. The color of the profile at ∼100 kpc suggests that the buildup of the intracluster light of A85 occurs by the stripping of massive (∼1010 M ⊙) satellites. The measured fraction of this light ranges from 8%–30% in g, depending on the definition of intracluster light chosen.