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Session 74 - Supernova Remnants.
Display session, Thursday, June 13
We conduct an analytic and numerical study of the dynamics of supernova-remnant evolution from the ejecta-dominated stage through the Sedov-Taylor stage, the stages which precede the onset of dynamically significant radiative losses. We emphasize that all remnants of a given form of ejecta and ambient-medium density distribution evolve according to a single universal solution. Use of dimensionless quantities constructed from the characteristic dimensional parameters of the problem---the ejecta energy, ejecta mass, and ambient density---makes the universality manifest. We present approximate analytic solutions for the motions of both the reverse and blastwave shocks for power-law density ejecta and uniform-density ambient media. These solutions follow the shocks through the entire nonradiative evolution of a remnant and across multiple periods of self-similarity and non-self-similarity. We elucidate the dependence of the ejecta-dominated evolution on the ejecta power-law index n by developing a general solution for all n and explaining its relation to the solutions of Chevalier (1982) and Nadyozhin (1985) for n>5 and Hamilton amp; Sarazin (1984) for n=0. We demonstrate excellent agreement between our analytic solutions and numerical simulations. These solutions should be valuable in describing remnants such as SN 1006, Tycho, Kepler, Cassiopeia A, and other relatively young SNRs that are between the early ejecta-dominated stage and the late Sedov-Taylor stage. X-ray emission from the reverse and blastwave shocks in both our analytic and numerical models is related to observations of young remnants. Finally, we describe the existence of an early radiative period for the reverse shock and present results of the evolution for power-law density ambient media.
Program listing for Thursday