Radio Galaxy Environments
All massive galaxies host supermassive black holes (SMBHs). Relativistic outflows from these SMBHs have been the driving force that has shaped the evolution of stars, gas, galaxies and the intergalactic medium (IGM) over most of cosmic time. But beyond this broad statement, the respective roles of different (and sometimes competing) physical processes driven by SMBHs and their outflows are not understood. Radio continuum emission is a powerful probe of this interplay, because it is produced under a range of conditions, does not substantially suffer from extinction, and with new wide-field facilities can be studied over the entire sky.
In this project, CAASTRO is using radio continuum surveys from SKA pathfinders and related facilities to quantify the impact of SMBH outflows on the evolution of stars and galaxies. By employing wide fields, very broad bandwidths, and new analysis techniques, we aim to address three related questions:
- How do SMBHs pollute their large-scale environments with thermal gas, relativistic particles and magnetic fields?
- What are the properties and environments of radio galaxies at their earliest and final stages of evolution?
- How have active galaxies and their environments evolved over cosmic time?
| The coloured pixels represent the Faraday rotation measure (RM), in rad/m^2, probing the magneto-ionic environment of the radio galaxy Centaurus A. The RMs of background radio sources seen through the lobes are represented by circles whose size corresponds to the magnitude of the RM. (O'Sullivan et al. 2013)