Title: Evidence of Runaway Gas Cooling in the Absence of Supermassive Black Hole Feedback at the Epoch of Cluster Formation

Speaker: Shuang Liu (Purple Mountain Observatory, Chinese Academy of Sciences)

Time: 12:00, November 9, 2021

Location: 3-201, PMO Xianlin Campus

Abstract: Cosmological simulations, as well as mounting evidence from observations, have shown that supermassive black holes play a fundamental role in regulating the formation of stars throughout cosmic time. This has been clearly demonstrated in the case of galaxy clusters in which powerful feedback from the central black hole is preventing the hot intracluster gas from cooling catastrophically, thus reducing the expected star formation rates by orders of magnitude. These conclusions, however, have been almost entirely based on nearby clusters. Based on new Chandra X-ray observations, the first observational evidence for massive, runaway cooling occurring in the absence of supermassive black hole feedback can be seen in the high-redshift galaxy cluster SpARCS104922.6+564032.5 (z=1.709). The hot intracluster gas appears to be fueling a massive burst of star formation that is offset by dozens of kpc from the central galaxy. The burst is co-spatial with the coolest intracluster gas. These observations show the dramatic impact when supermassive black hole feedback fails to operate in clusters, indicating that runaway cooling may be a new and important mechanism for fueling massive bursts of star formation in the highest overdensities in the early universe.