Presentation #428.02 in the session Galaxy Clusters.
Observations from state-of-the-art facilities have revolutionized our view of the inter-relation between ICM, optical emission-line gas, and galaxies clusters. However, how the feedback from active galactic nuclei (AGN) operates on the hot atmospheres is still not fully understood. This talk will present a statistical study of X-ray cavities in Planck-selected clusters using Chandra observations to provide further insight into how AGN feedback operates on clusters. The Planck cluster sample is an all-sky nearly unbiased mass-selected sample of galaxy clusters at moderate redshift (z<0.35), which could reflect the entire AGN feedback cycle at the centers of galaxy clusters.
Based on X-ray image analysis of 63 CC clusters and 101 NCC Planck selected clusters, we report that 28 of the 164 clusters show X-ray cavities, which corresponds to a detection fraction of 17%. After correcting by resolution to match the high-z SPT-SZ sample, the detection fraction decreases to 9%, consistent with the high-z sample, hinting that the AGN feedback has not evolved across almost 8 Gyr. This finding strongly agrees with the lack of evolution of cool-core clusters fraction. Furthermore, we calculate the cavity power, and find that most systems have enough AGN heating to offset the radiative losses of the intracluster medium (ICM). By studying the dynamic state of clusters, the observations hint that ICM influences the distribution and morphology of cavities.
By analyzing MUSE observations, we find that the Halpha filaments are preferentially located behind or around the X-ray cavities, indicating the important role of the AGN feedback on the condensation of gas. Nevertheless, a few Halpha emitting clusters lack X-ray cavities, meaning either different heating mechanisms or different timescales for the dissipation of the cavities and Halpha emitting gas.