The XMM-Newton long look of NGC 1365: uncovering of the obscured X-ray source

We present an analysis of the extreme obscuration variability observed during an XMM-Newton 5-d continuous monitoring of the active galactic nuclei (AGN) in NGC 1365. The source was in a reflection-dominated state in the first similar to 1.5 d, then a strong increase in the 7-10 keV emission was observed in similar to 10 h, followed by a symmetric decrease. The spectral analysis of the different states clearly shows that this variation is due to an uncovering of the X-ray source. From this observation, we estimate a size of the X-ray source D(S) < 10(13) cm, a distance of the obscuring clouds R similar to 10(16) cm and a density n similar to 10(11) cm(-3). These values suggest that the X-ray absorption/reflection originates from the broad-line region clouds. This is also supported by the resolved width of the iron narrow K alpha emission line, consistent with the width of the broad H beta line.