Schedule May 8, 2000
Radiative Fluids
Jon Arons (Univ. California, Berkeley)
I review the basic properties of accretion powered pulsars, with particular reference to their being locally extremely super Eddington emitters of X-rays. I outline a simple model of an diffusion-advection model of an accretion mound at a magnetic polar cap, summarize the results of a WKB analysis of the "photon bubble" instability appropriate to these highly magnetized objects. I show a number of results of 2D radiation gas dynamic simulations of this instability, which lead to a higly structured flow below the accretion shock, in which low density, radiation filled pockets form, with elongated structure along B. The effect of these pockets formation and disappearance, through radiation being fed into the overlying shock, then to be swept down and emitted from the base of the mound, on the time series of the emergent luminosity is shown, and compared to recent observations of the fluctuations in the light curve of Cen X-3, with the conclusion that these fluctuations may be the first clear observation of photon bubbles in a super Eddington flow.

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