摘要：Galaxy clusters can host multiphase gas both in the central region and in the outskirts. The centers of cool-core clusters often harbor extended multiphase filaments that shine brightly in Halpha and CO. These filaments are thought to be created via thermal instability of the hot intra-cluster medium (ICM) under the influence of supermassive black hole (SMBH) "feedback". We have analyzed the kinematics of the central filaments in more than a dozen nearby clusters by measuring their velocity structure functions. We find that the motions of the filaments are directly linked to the activities of the SMBHs. In all systems, the VSF is steeper than the classical Kolmogorov expectation and the slopes vary from system to system. In a small subset of clusters, the VSF of the outer filaments flattens on small scales to a slope consistent with classical Kolmogorov. This suggests that in the central tens of kpc, the ICM is dominated by bulk motions induced by SMBH feedback, and turbulence cascade can only be detected further away from the SMBH. Heating due to turbulent dissipation is subdominant. We have also analyzed multiphase gas in the tails of jellyfish galaxies which are formed as a result of ram pressure stripping. We find that the motion of the tail is dominated by turbulence driven by Kelvin-Helmholtz instability, which quickly overwhelms the original ISM turbulence. We compare the kinematics of different phases of the ICM, including the hot X-ray plasma, the warm ionized gas, and the molecular component. Within the observed dynamical range, all different phases appear well-coupled kinematically. Using cooler gas as a tracer of the hot plasma, we can put a constraint on the isotropic viscosity to be below 0.01% Spitzer level.
报告人简介：Yuan Li received her PhD from Columbia University in 2014. She was a postdoc fellow at UC Berkeley before joining the University of North Texas as an assistant professor in 2020. Yuan is mainly a theoretical/computational astrophysicist working in the general field of galaxy evolution. Her research interests include galaxy clusters and massive galaxies; the feeding and feedback of supermassive black holes; star formation and galaxy evolution; the interstellar medium, the circum-galactic medium, and the intra-cluster medium.