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

TL;DR

This study analyzes a 130 ks XMM-Newton observation of Fairall 9, revealing a 'softer-when-brighter' X-ray behavior, a clean nucleus without warm absorbers, and a relativistic disc-reflection spectrum indicating an intermediate black hole spin.

Contribution

First detailed X-ray spectral analysis of Fairall 9 showing a clean nucleus and constraining its black hole spin using relativistic reflection modeling.

Findings

'Softer-when-brighter' X-ray behavior observed.

No significant warm-absorber detected.

Black hole spin estimated as approximately 0.39.

Abstract

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 for radio-quiet type I Seyfert galaxies. Moreover, we analyse the high spectral-resolution data of the reflection grating spectrometer and we did 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-fit spin parameter of $\alpha=0.39^{+0.48}_{-0.30}$.