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Session 53 - SNs, Planetaries and Circumstellar Disks.
Display session, Wednesday, June 10
We present an initial evaluation of the role of the Richtmeyer-Meshkov (RM) instability in supernova remnant (SNR) formation. Although the Rayleigh-Taylor (RT) instability is most often considered in the canonical account of SNR formation, the theoretical penetration depths for the RM instability suggest that it could play a more significant role, particularly in the early stages. Here we present and discuss theory and simulations to evaluate this possibility. We apply some recent theory of RM to the SNR case to show that it is plausible that RM could play a significant role. One must note, however, that in some key respects the SNR system does not satisfy the assumptions used in such theory. This motivates simulations. Accordingly, we have used the code PROMETHEUS to perform a sequence of 2D hydrodynamic simulations in order to test this possibility. Our choice of parameters corresponded to typical Type Ia conditions and is motivated by the work of Jun and Norman [ApJ 465: 800 1996], which we reproduced for the same initial conditions. We have explored a variety of initial conditions, with various perturbed interfaces to seed RM and with or without fluctuations to seed RT. Here we discuss in detail a case in which we impose a severe RM perturbation in the expanding ejecta behind the reverse shock. The perturbation produces significant early RM growth, with spikes penetrating from the contact surface to the forward shock. Then the RM instability weakens, RT growth eventually dominates, and the perturbation of the forward shock diminishes. We conclude that the RM instability of a single perturbation is unlikely to account for the observed radio and x-ray structures which extend to the forward shock. We speculate that the RM instability might account for such observations if it is continuously reseeded.
Program listing for Wednesday