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Occultation measurement of the size of the X-ray emitting region in the Active Galactic Nucleus of NGC 1365

G. Risaliti·M. Elvis·G. Fabbiano·A. Baldi·A. Zezas·M. Salvati
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Abstract

We present an occultation of the central X-ray emitting region in the Seyfert Galaxy NGC 1365. This extreme spectral variation (from Compton-thin to reflection-dominated and back to Compton-thin in four days) has been caught in a ten days Chandra monitoring campaign consisting of six short (15 ks) observations performed every two days. We discuss the implications of this occultation within the scenario of a Compton-thick cloud crossing the line of sight of the X-ray source. We estimate a source size R<10^14 cm and a distance of the cloud from the source D<10^16 cm. This direct measurement confirms the theoretical expectations of an extremely compact X-ray source, and shows that the Compton-thick circumnuclear gas is located at a distance from the center on the scale of the Broad Line Region.

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G. Risaliti, M. Elvis, G. Fabbiano, A. Baldi, A. Zezas, M. Salvati. 2007-03-08. Occultation measurement of the size of the X-ray emitting region in the Active Galactic Nucleus of NGC 1365. https://doi.org/10.1086/517884

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