A relativistic iron line in the X-ray spectrum of the atoll source 4U 1705-44questionMark

We propose a ToO (triggered) observation with XMMNewton of the atoll source 4U170544 during a soft state. A Chandra observation of this source clearlyindicate the presence of a broad (sigma virgul 0.7 keV) iron line. Both arelativistic disc line and a thermal Comptonization broadening fit well the lineprofile. The superior sensitivity at the iron line energy of XMMNewton isneeded to give a definite answer to the problem of the origin of the broad ironline.