Physics of the neutron star magnetosphere in Supergiant Fast X-ray Transients

Supergiant Fast Xray Transients show rare outbursts,while most of the time theyare in a fainter state.The physical mechanism driving this behavior iscontroversial, with two competing models\\: quasispherical settling accretionand the propeller mechanism. Our analysis of archival XMM observations allowedus to select SFXT flares in an automatic way and to compare their timescaleswith the theory of magnetospheric instability in the NS magnetosphere. To get astatistically robust comparison with the models, it is crucial to enlarge thenumber of flares.This will result in the determination of the dimensionlessparameters involved in the Rayleigh Taylor instability, impossible to obtainfrom the theory, directly probing the physics of the NS magnetosphere. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]