Predicting Sunyaev-Zel’dovich effect observations of galaxy cluster cavities with the Square Kilometre Array

Galaxy cluster X-ray cavities are inflated by relativistic jets that are ejected into the ICM by active galactic nuclei (AGN). AGN jets prevent predicted cooling flow establishment at the cluster centre, however the energy transfer process between the jets and the surrounding ICM is not well understood in existing studies.

Simulations have shown that the heating mechanism will depend on the type of gas that fills the cavities. A thermal and non-thermal distribution of electrons will produce different Sunyaev Zel’dovich (SZ) effect signals, mostly in the form of suppression. This suppression is quantified as the suppression factor f, derived from a generalisation of the SZ effect across the entire cluster, including the cavities. This thesis explores enhancements to prior constraints on the cavity gas type by simulating suppression factor observations. Simulations of the Square Kilometre Array (SKA) are conducted, which observe a range of cluster cavities across redshifts, and predict the optimum way to measure f in future observations.

I find that the SKA can constrain the suppression factor in the cavities of cluster MS 0735.6+7421 (MS0735) with as little as 4 hours, and the smallest observable suppression factor is f ≈ 0.42. Additionally, while the SKA may distinguish between possible thermal or non-thermal suppression factor values within the cavities of MS0735 if it observes for more than 8 hours, determining the gas type of other clusters will likely require multiple frequency observations. The effect of cavity line of sight (LOS) position is also studied, where degeneracies between LOS position and measured value of f are found. Finally, I find that for small cavities (radius < 80kpc) at high redshift (z ≈ 1.5), the proposed high frequencies of the SKA (23.75GHz - 37.5GHz) will be optimal, and that including MeerKAT antennas will improve future observations.