Occultation Measurement of the Size of the X-Ray-emitting Region in the Active Galactic Nucleus of NGC 1365
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 4 days) has been caught in a 10 day Chandra monitoring campaign consisting of six short (15 ks) observations performed every 2 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<=1014 cm and a distance of the cloud from the source D<=1016 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2007
- DOI:
- 10.1086/517884
- arXiv:
- arXiv:astro-ph/0703173
- Bibcode:
- 2007ApJ...659L.111R
- Keywords:
-
- Galaxies: Active;
- Galaxies: Individual: NGC Number: NGC 1365;
- Astrophysics
- E-Print:
- 12 pages, 2 figures. ApJ Letters, in press