Observing Rayleigh-Taylor Stable and Unstable Accretion Through a Kalman Filter Analysis of X-Ray Pulsars in the Small Magellanic Cloud

Abstract

Global, three-dimensional magnetohydrodynamic simulations of Rayleigh-Taylor instabilities at the disk-magnetosphere boundary of rotating, magnetized compact stellar objects reveal that accretion occurs in three regimes: the stable regime, the chaotic unstable regime, and the ordered unstable regime. Here we track stochastic fluctuations in the pulse period P(t) and aperiodic X-ray luminosity L(t) time series of 24 accretion-powered pulsars in the Small Magellanic Cloud using an unscented Kalman filter to analyze Rossi X-ray Timing Explorer data. We measure time-resolved histories of the magnetocentrifugal fastness parameter ω(t) and we connect ω(t) with the three Rayleigh-Taylor accretion r..