Feedback processes in astrophysical systems from galaxies to clusters: A multi-wavelength approach

Abstract

Extragalactic systems, such as galaxies and galaxy clusters, are not static objects confined within defined spatial boundaries; rather, they are dynamic and continually evolving and growing. The growth of these objects on a large-scale is influenced by various astrophysical feedback events, including supernovae, galactic winds, and black hole activity, leading to inflows and outflows of matter. These events have a reach that extends beyond the systems themselves, impacting the larger cosmic environment. This thesis explores the interactions between galaxies, the circumgalactic medium (CGM) which surrounds the individual galaxies and galaxy clusters, focusing on feedback mechanisms using survey data from different telescopes.Three projects are presented that investigate different feedback mechanisms and their impact on structure growth. In the first project we use radio observations from the MeerKAT telescope to measure magnetic fields in the CGM. We measure the rotation measure around foreground star-forming galaxies to derive constraints on the magnetic field strength of the CGM. In the second project we use X-ray data from the eROSITA telescope, public optical data from the legacy survey and radio data from the ASKAP telescope to investigate feedback from Active Galactic Nuclei (AGN) in galaxy clusters. In the third project we stack data from the ACT telescope to measure the thermal Sunyaev-Zel’dovich effect around massive galaxies to study AGN feedback and how it affects the CGM of these galaxies. Collectively, these studies investigate the complex interplay between the gas contained in galaxies, the CGM and clusters, especially focusing on feedback induced processes like in- and outflows of gas and how these processes affect the structure growth. All these works have in common that comparisons of our observational data with simulation data reveal discrepancies. This demonstrates the need for numerical simulations with higher resolution that take into account different boundary conditions, as well as the need for new telescopes that generate deeper data and cover larger celestial areas.