In the Mouth of the Whale
Paul J. McAuley2012

Fomalhaut was first colonised by the posthuman Quick, who established an archipelago of thistledown cities and edenic worldlets within the star's vast dust belt. Their peaceful, decadent civilisation was swiftly conquered by a band of ruthless, aggressive, unreconstructed humans who call themselves the True, then, a century before, the True beat back an advance party of Ghosts, a posthuman cult which colonised the nearby system of Beta Hydri after being driven from the Solar System a thousand years ago. Now the Ghosts have returned to Fomalhaut, to begin their end game: the conquest of its single gas giant planet, a captured interstellar wanderer far older than the rest of Fomalhaut's system. At its core is a sphere of hot metallic hydrogen with strange and powerful properties based on exotic quantum physics. The Quick believe it is inhabited by an ancient alien Mind; the True believe it can be developed into a weapon, and the Ghosts believe it can be transformed into a computational system so powerful it can reach into their past, collapse timelines, and fulfil the ancient prophecies of their founder.