Effects of the photo-ionized absorber on the continuum spectra of EXO 0748 676

Abstract

We report on the analysis of XMM-Newton archival data of EXO 0748-676. We studied changes of the continuum spectra due to the presence of photo-ionized plasma on the line of sight. We show that the ionization degree of the plasma could change largely during the X-ray bursts and the dips. These changes can significantly modify the soft-band spectrum, which was in fact observed from EXO 0748-676. We discuss the effect of the photo-ionized plasma on the continuum spectra in comparison with a frequently used model such as partial covering absorption.