Disentangling Multiple Gas Kinematic Drivers in the Perseus Galaxy Cluster

Abstract

Galaxy clusters, the Universe's largest halo structures, are filled with 10-100 million degree X-ray-emitting gas. Their evolution is shaped by energetic processes such as feedback from supermassive black holes (SMBHs) and mergers with other cosmic structures. The imprints of these processes on gas kinematic properties remain largely unknown, restricting our understanding of gas thermodynamics and energy conversion within clusters. High-resolution spectral mapping across a broad spatial-scale range provides a promising solution to this challenge, enabled by the recent launch of the XRISM X-ray Observatory. Here, we present the kinematic measurements of the X-ray-brightest Perseus cluster with XRISM, radially covering the extent of its cool core. We find direct evidence for the presence of at least two dominant drivers of gas motions operating on distinct physical scales: a small-scale driver in the inner ~60 kpc, likely associated with the SMBH feedback; and a large-scale driver in the outer core, powered by mergers. The inner driver sustains a heating rate at least an order of magnitude higher than the outer one. This finding suggests that, during the active phase, the SMBH feedback generates turbulence, which, if fully dissipated into heat, could play a significant role in offsetting radiative cooling losses in the Perseus core. Our study underscores the necessity of kinematic mapping observations of extended sources for robust conclusions on the properties of the velocity field and their role in the assembly and evolution of massive halos. It further offers a kinematic diagnostic for theoretical models of SMBH feedback.