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

Abstract

We present an analysis of the extreme obscuration variability observedduring an XMM-Newton 5-d continuous monitoring of the active galacticnuclei (AGN) in NGC 1365. The source was in a reflection-dominatedstate in the first similar to 1.5 d, then a strong increase in the 7-10keV emission was observed in similar to 10 h, followed by a symmetricdecrease. The spectral analysis of the different states clearly showsthat this variation is due to an uncovering of the X-ray source. Fromthis 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 adensity n similar to 10(11) cm(-3). These values suggest that the X-rayabsorption/reflection originates from the broad-line region clouds.This is also supported by the resolved width of the iron narrow K alphaemission line, consistent with the width of the broad H beta line.