Multipeaked X-ray bursts from 4U/MXB 1636-53 - Evidence for burst-induced accretion disk coronae

The specific features of multipeaked X-ray bursts from 4U/MXB 1636-53, which are relatively weak and show no correlated photospheric radius expansion or contraction near the burst maximum, are explained using a model in which the observed luminosity is the sum of the direct component from the central source attenuated through an accretion disk corona and a component due to diffuse scattering by the corona. According to this model, the central peak in the triple-peaked burst results from an enhanced scattering emissivity of the direct component. At large inclination angles, the direct component may be unobservable; a burst detected via the scattered component only would be relatively short, weak, and would have similar rise and decay times. The direct and scattered components can be distinguished by X-ray polarimetry.