An XMM-Newton view of the 'bare' nucleus of Fairall 9

We present the spectral results from a 130-ks observation, obtained from the X-ray Multi-Mirror Mission-Newton (XMM-Newton) observatory, of the type I Seyfert galaxy Fairall 9. An X-ray hardness ratio analysis of the light curves reveals a 'softer-when-brighter' behaviour which is typical of radio-quiet type I Seyfert galaxies. Moreover, we analyse the high spectral resolution data of the reflection grating spectrometer and we do not find any significant evidence supporting the presence of warm absorber in the low X-ray energy part of the source's spectrum. This means that the central nucleus of Fairall 9 is 'clean' and thus its X-ray spectral properties probe directly the physical conditions of the central engine. The overall X-ray spectrum in the 0.5-10 keV energy range, derived from the EPIC data, can be modelled by a relativistically blurred disc reflection model. This spectral model yields for Fairall 9 an intermediate black hole best-fitting spin parameter of α= 0.39+0.48 − 0.30.