AGNs to the IGM: Tracing the Energy Flow Through Radio Galaxies

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JonesAST-0071167This proposal is to use both theoretical 3-D MHD modeling constrained by X-ray observations and low-frequency radio imaging to study the deposition and diffusion of energy in the jets and lobes of radio galaxies. The goal is to relate the magnetic field and cosmic rays to the jet dynamics and radio-galaxy evolution.The proposed work aims to add fundamental insights to the understanding of interactions between the enormously energetic phenomena originating in the central cores of some galaxies and the vast, gaseous environments around those galaxies. Energetic streams of hot plasma appear to be expelled from the galactic cores at speeds approaching the speed of light. When those streams plow into the diffuse plasma surrounding the galaxy the interacting regions produce relativistic electrons and become illuminated. Those structures are known as Radio Galaxies and they not only emit radiation at radio wavelengths but also in the optical and x-ray regions. For the first time, new observational capabilities will enable us to directly compare radio and X-ray emissions produced by the same electron populations. The radio emissions are a consequence of weak magnetic fields pervading the interaction regions, while the signature X-rays result from collisions between those electrons and photons in the Cosmic Microwave Background. Simultaneous measurements of both is necessary to find measures of the strengths of the magnetic fields and the properties of the electron populations. That information, in turn is crucial input into efforts to infer the dynamical events leading to the radio structures. The investigators are in position to carry out highly sophisticated numerical simulations of these objects, studying both the relationships between the energetics of the plasma flows and the emissions that can be observed from earth. Those studies will be followed by more general exploration of the evolution of these vast dynamical structures, so as to understand better the ways in which radio galaxies contribute to the properties of the gaseous media that fill clusters of galaxies. That topic is currently of broad interest in the study of cosmic structure formation.Funding for this project was provided by the NSF program for Extragalactic Astronomy & Cosmology (AST/EXC).****