The properties of the absorbing and line emitting material in IGR J16318-4848

Abstract

We have performed a detailed analysis of the XMM-Newton observation of IGR J16318-4848, to study the properties of the matter responsible for the obscuration and for the emission of Fe and Ni lines. Even if the line of sight material has a column density of about 2x10^24 cm^-2, from the Fe Kalpha line EW and Compton Shoulder we argue that the matter should have an average column density of a few x10^23 cm^-2, along with a covering factor of about 0.1-0.2. The iron Kalpha line varies on time scales as short as 1000 s, implying a size of the emitting region smaller than about 3x10^13 cm. The flux of the line roughly follows the variations of the continuum, but not exactly, suggesting a variation of the geometrical properties of the emitting region on similar time scales.