Jet Feedback on Groups and Galaxy Clusters

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The cosmological concordance model provides an astonishing match to data of large-scale cosmological surveys, but on smaller scales—where baryonic effects start to become dominant— the situation is less clear. In particular, the halo mass and galaxy luminosity distributions differ significantly so that the star conversion efficiency has to be a strong function of halo mass. Gas is less efficiently converted to stars towards the scale of galaxy groups and clusters. The interplay of cooling gas, subsequent star formation, and nuclear activity appears to be tightly coupled to a self-regulated feedback loop that may explain this cosmological conundrum. The main goal of this project aims at studying the non-thermal aspect of the active galactic nucleus (AGN) feedback loop in the vicinity of the jet and compares observed and synthetic radio emission to calibrate feedback. To this end, this project uses LOFAR data (in particular newly available high-resolution long-baseline data) and state-of-the-art cosmological magneto-hydrodynamical simulations with cosmic ray and AGN jet physics of galaxy groups and clusters to explore how jets transfer energy and momentum to the intracluster medium (ICM) and regulate cooling and star formation. Results from this project serve as large-scale constraints to small-scale relativistic jet models that will be pursued in this proposed research unit in particular by the Mercator fellow Manel Perucho. Our main research questions are: 1. How is feedback energy transferred from the AGN jets to the cooling ICM and which observational signatures demonstrate this unambiguously? 2. Can cosmic ray heating from AGN jets reproduce the observed bimodality of the distribution of cool core and non-cool core clusters? 3. Which parameters determine the morphology of AGN jets (luminosity, environment, or composition) and how can we relate this to feedback?