Galaxy Disruption as the Origin of Intracluster Light in the Coma Cluster

Although the existence of a faint background of starlight in the core of the Coma cluster has been well established (1,2), its origin is uncertain. This vast sea of stars could have formed outside the galaxies, using gas left over from the time of the cluster’s birth. Alternatively, it might be the accumulated debris generated by interactions between the galaxies over the lifetime of the cluster (3). Here we report the discovery of three large, low surface brightness features in the Coma cluster; the most spectacular is a plume-like structure, 130 kpc long, in the cluster’s heart. These structures will disperse over the next one to two billion years, thereby enhancing the general background light. If this epoch is typical, we argue that a significant fraction – perhaps even most – of the intracluster light results from a steady accumulation of tidal debris generated during galaxy-galaxy and galaxy-cluster interactions.