Tidal Disruption of Super Star Clusters as the Origin of Bluish Light at the Inner Region of the Perseus Cluster Central Galaxy

Abstract Relatively blue light extends beyond a spiral disk from a radius of ∼5 kpc out to ∼14 kpc from the center of NGC 1275. Analyses of its spectrum and broadband colors reveal a population of young stars having subsolar metallicities superposed on a dominant population of old stars having supersolar metallicities. The young stars have a characteristic age of ∼160 Myr and may span ages of a few hundred Myr, similar to that of stars comprising the central spiral disk, and a total mass of about one-third that of this disk for a combined stellar mass (at birth) of ∼4 × 10 9 M ⊙ . A multitude of arc-like features embedded in the extended blue light have brightnesses comparable to the somewhat older (∼500 Myr) super star clusters (SSCs) projected against the central spiral disk. The SSCs have a relatively shallow mass function, suggesting that the tidal disruption of an initially larger population that we estimate could have had an initial total mass (far) exceeding ∼1 × 10 9 M ⊙ gave rise to the extended blue light—the arc-like features corresponding to stellar streams tracing disrupted star clusters—and perhaps also the central spiral disk. We speculate that, beginning about 500 Myr ago, an enhanced episode of active galactic nucleus activity in NGC 1275, leaving still visible X-ray bubbles, induced a vigorous cooling of the intracluster medium to fuel the formation of numerous star clusters: many were tidally disrupted to leave bluish light at the inner region of this galaxy, with the survivors being the SSCs projected against the central spiral disk.