RSAA Colloquia / Seminars / Feast-of-Facts: Tuesday, 27 January 2015, 11:00-12:00; Duffield Lecture Theatre

Mohammad Nawaz

"Interaction of Hydra A jets with the Intracluster medium"

An important research area of modern astronomy is to understand the physics of jets from Active Galactic Nuclei (AGN) and their interaction with the interstellar medium (ISM) or intracluster medium (ICM). My thesis aims to understand the energetics and composition of the jet near its origin, and its interaction with the ICM, focusing on detailed models of the inner structure of a spectacular radio source Hydra A. The key features of my modelling are that 1) I identify the four bright knots in the northern jet of Hydra A as biconical reconfinement shocks, which result when an over-pressured jet starts to come into equilibrium whit the galactic atmosphere 2) The curved morphology of the source and the turbulent transition of the jet to a plume are produced by the dynamical interaction of a precessing jet with the ICM. In my thesis, I provided an innovative theoretical approach to estimate the jet velocity from the information of the inner jet knots and the oscillation of the jet boundary. I also explored the complex morphology of the source and the heating of the ambient medium via the forward shock using a three dimensional precessing jet-ICM interaction model. With the 3D models I successfully reproduced key features of the source, for example, i) Four bright knots along the jet trajectory at approximately correct locations, 2) The curvature of the jet within 10 kpc, 3) The turbulent transition of the jet to a plume, and 4) A misaligned bright knot in the turbulent flaring zone. From my model I determined that the heating of the atmosphere by the jet would be gentle, which is consistent with the assessment of the physics of cooling flow.