Study of the spectral soft excess in high luminosity transient pulsars

Many accreting Xray pulsars show a lowenergy soft excess in their spectra,whose origin is still unclear. The study of this feature is essential to castlight on the physical processes ongoing in these sources. Due to the lowabsorption, the transient pulsars in the SMC, which can reach high luminosities(Lx>1E38 erg/s), are ideal targets for these studies. Very recently, we obtainedan observation of RX J0059.27138 in outburst: it allowed us to detect and studyat an unprecedented level of detail its soft excess, discovering severalemission and absorption features, which provide strong constraints on the sourceemission processes. We propose a ToO observation of another transient pulsar inthe SMC, in case of a bright outburst, in order to characterize its soft excess. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]