Teo Muñoz-Darias: Bowen Blend Echo-tomography of Neutron Star LMXBs

Teo gave an overview of a technique which picks out reprocessed emission lines (the Bowen blend) from the irradiated companion star in a neutron star binary. The continuum emission, by contrast, is swamped by the contribution from the disk. Using simultaneous X-ray/optical observations you can look for delayed echoes of X-ray variability. The time delays then tell you about the properties of the binary system as a function of orbital phase. The group are currently writing up an analysis of 4U 1636-536 (for which, fortuitously, they observed 3 reprocessed X-ray bursts), to complement an analysis of Sco X-1 published last year. In both cases the observed delays are consistent with reprocessing from the companion star for the Bowen blend lines, and the accretion disk for the continuum.