Session 16 - QSOs and Active Galaxies.
Oral session, Monday, June 08
Presidio,

## [16.06] SAX Observations of the Maser AGN ESO 103-G35

B. Wilkes, S. Mathur (SAO), F. Fiore (SAO and BeppoSAX SDC), A. Antonelli (BeppoSAX SDC)

The sub-parsec masing disk recently found to be orbiting a \sim 10^7 solar mass black hole in the Seyfert 2 galaxy, NGC 4258, provides the most compelling evidence to date for the existence of a massive black hole in the nucleus of a galaxy. The disk is edge-on, the X-ray spectrum is heavily absorbed, and an active nucleus is visible in polarised light. Nearly all AGNs which contain maser sources and have X-ray observations show strong X-ray absorption consistent with an edge-on disk, suggesting that many of them may harbour active nuclei in their cores. We have made SAX observations of the Seyfert 2 galaxy ESO103-G35, which contains a nuclear maser source and is known to be heavily absorbed in the X-rays. We present preliminary analysis of the X-ray spectrum which extends up to \sim 200 keV with no detectable contribution from a reflected component, shows a \sim 300 keV equivalent width, cold, narrow Fe K\alpha line and absorption, N_H \sim 2 \times 10^23 cm^-2, consistent with earlier results.