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arXiv · 2212.08185

Tracking hidden magnetospheric fluctuations in accretion-powered pulsars with a Kalman filter

A. Melatos·N. J. O'Neill·P. M. Meyers·J. O'Leary
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Abstract

X-ray flux and pulse period fluctuations in an accretion-powered pulsar convey important information about the disk-magnetosphere interaction. It is shown that simultaneous flux and period measurements can be analysed with a Kalman filter based on the standard magnetocentrifugal accretion torque to generate accurate time-dependent estimates of three hidden state variables, which fluctuate stochastically and cannot be measured directly: the mass accretion rate, the Maxwell stress at the disk-magnetosphere boundary, and the radiative efficiency of accretion onto the stellar surface. The inferred fluctuation statistics carry implications for the physics of hydromagnetic instabilities at the disk-magnetosphere boundary and searches for continuous gravitational radiation from low-mass X-ray binaries.

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A. Melatos, N. J. O'Neill, P. M. Meyers, J. O'Leary. 2022-12-15. Tracking hidden magnetospheric fluctuations in accretion-powered pulsars with a Kalman filter. https://doi.org/10.3847/1538-4357/acab5a

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