McNamara@65: Understanding Feedback in Galaxies and Clusters

The impact of relativistic jets from AGN on galaxy and cluster atmospheres first became apparent in high resolution X-ray images more than two decades ago.  The jets inflate large bubbles, drive weak shocks and sound waves, and lift low-entropy, metal-rich gas into the galaxy halo.  Clear correlations between the jet power and large-scale radiative cooling losses followed these discoveries and imply a strong feedback loop likely mediated by the AGN's fuel supply.  Optical, IR and sub-mm observations reveal ionized, neutral and molecular gas flows drawn up into long, thin filaments in the wakes of rising bubbles.  Despite the energy input by AGN, central radiative cooling times remain well below a Gyr and hot atmospheres appear to have low levels of turbulence.  Currently, our understanding lags behind these observational breakthroughs.  We do not yet know how the energy emitted by an AGN on small scales can be efficiently coupled to gas on galaxy scales.

Mirroring the rise of feedback, Brian McNamara's research and publications chart many pivotal advances.  From the earliest Chandra observations of cavities, through the empirical relations evidencing feedback, to the massive multiphase gas flows lifted by jet activity, Brian has long been at the forefront of the field.  His impact perhaps best likened to a favourite target - MS0735.  With the arrival of XRISM, JWST, eROSITA and next generation radio observatories, we are entering the next exciting era of discoveries and anticipating a broader understanding of galaxy and black hole coevolution across cosmic time.  The aim of this workshop is to summarise and expand our knowledge of AGN feedback, and celebrate Brian McNamara's landmark achievements in our field.