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Nonthermal Processes of Fast Outflows from Astrophysical Objects


Sun,  Xiaona
Division Prof. Dr. Werner Hofmann, MPI for Nuclear Physics, Max Planck Society;

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Sun, X. (2017). Nonthermal Processes of Fast Outflows from Astrophysical Objects. PhD Thesis, Ruprecht-Karls-Universität, Heidelberg.

Cite as: https://hdl.handle.net/21.11116/0000-0000-2A7E-5
Outflows are ubiquitous phenomena in the universe. They have been widely observed in both Galactic and extragalactic objects. In this thesis, we analyze three individual sources. Firstly, we re-analyze the high energy gamma-ray data of Fermi-LAT on the giant lobes of Centaurus A. We utilize for the first time the Planck observations to derive the fluxes of the lobes. The multiwavelength SEDs reveal a possible leptonic+hadronic origin of the non-thermal emission. Secondly, we re-analyze Chandra observations of the M87 jet with a total exposure time of 1500 kiloseconds to explore the X-ray emission characteristics along the jet. The variabilities of the nucleus and HST-1, as well as the photon spectra for all knots are investigated. Fitting the radio to Xray SEDs assuming a synchrotron origin, we show that a broken power-law electron spectrum allows a satisfactory description of the SEDs for most knots except for B, C and D, for which an additional component is needed. We discuss the implications and suggest that a stratified jet model may account for the differences. Finally, we derive the energy distribution of ultrarelativistic electron in G1.9+0.3, which is the youngest known SNR in the Galaxy, under the assumption that the detected X-ray with Chandra and NuSTAR are of entirely synchrotron origin. The electron acceleration is found to be an order of magnitude slower than the maximum rate provided by the shock acceleration in the nominal Bohm diffusion regime. We discuss the resultant implications in the context of contribution of SNRs to the Galactic Cosmic Rays at PeV energies.