Understanding young active galaxies across the radio spectrum

Abstract:

The lifecycle of active galaxies is an open question in modern astronomy. In particular, not all active galaxies are active radio galaxies, and it is not obvious why. In this talk I’ll discuss my thesis work on these active radio galaxies, completed as part of the First Large Absorption Survey in HI, and conducted with the Australian SKA Pathfinder (ASKAP-FLASH). Early on, we realised many HI detections in ASKAP-FLASH were made towards so-called ‘Peaked Spectrum’ sources, active galaxies in which the synchrotron jets are still embedded in the dense, nuclear gas of their host galaxy. I’ll discuss how we identify these objects from pre-existing survey data using a Bayesian framework, RadioSED, and how a multiwavelength analysis of the resulting samples shows many are distant, capable of probing galaxy-scale interactions at cosmic noon and beyond. Moving from observations to simulations, I’ll show how we can test the impact of system geometry and morphology on FLASH detection rates using cosmological simulations as a sandbox. Ultimately, I wish to highlight the role of peaked spectrum sources in studies of active galaxy evolution, jet-gas interactions, and the changing distribution of gas across the different ages of our Universe.

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