The XMM-Newton long look of NGC 1365: uncovering of the obscured X-ray source
Zezas, A.; Bianchi, S.; Guainazzi, M.; Elvis, M.; Miniutti, G.; Baldi, A.; Fabbiano, G.; Soria, R.; Matt, G.; Braito, V.; Reeves, J.; Salvati, M.; Risaliti, G.
United States, Italy, United Kingdom, Spain, France
Abstract
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 ~1.5 d, then a strong increase in the 7-10 keV emission was observed in ~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 DS < 1013 cm, a distance of the obscuring clouds R ~ 1016 cm and a density n ~ 1011 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 Kα emission line, consistent with the width of the broad Hβ line.