Fluid dynamics of relativistic beams flowing through channels and evolution of double radio sources |
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| Authors: | M Yokosawa |
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| Institution: | (1) Department of Physics, Hokkaido University, Sapporo, Japan |
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| Abstract: | Dynamical evolution of a relativistic beam ejected from a galactic centre is studied using the similarity method for the relativistic winds flowing through channels. The expansion phase is divided into two stages: A relativistic expansion and a non-relativistic expansion stage. By the dimensional analysis for a relativistic wind, the propagation law of the expanding wave front is obtained. When the front moves relativistically, the density of the ambient matter observed in the co-moving frame of the front increases by the Lorentz contraction and mass increment, and the propagation law obtained in the classical theory is modified by these relativistic effects. On the basis of a perturbation method, a new similarity method for a relativistic flow whose front velocity is varing with the expansion is presented. The flow structures of the relativistic wind are given. With the expansion of a beam, the inward-facing shock wave is more separated from the front of the outward-expanding shock wave and its shock strength becomes stronger than that of the outward-expanding shock wave when the ejected beam consists of energetic particles. The evolutions of the extragalactic double sources are considered. The relative position of the hot spot in the radio map is presented at each stage of the expansion and discussed with the observational radio maps. The time variation of the radio emission is predicted. |
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