An XMM-Newton view of the ‘bare’ nucleus of Fairall 9★

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 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 .

No signatures of black hole spin in the X-ray spectrum of the Seyfert 1 galaxy Fairall 9

“…The reason why Suzaku spectra for Fairall 9 have received the attention of several studies is that the good energy resolution of the CCD detectors for measuring the crucial Fe Kα line profile, combined with the simultaneous sensitive coverage above 10 keV, provides a significant advance over previous capabilities for constraining the X-ray reflection spectrum and fluorescent line emission. Early observations of Fairall 9 with ASCA (Reynolds 1997) and XMM-Newton (Gondoin et al 2001;Emmanoulopoulos et al 2011) lacked the high-energy coverage. Nevertheless, a broad Fe Kα line (the principal feature required for constraining black-hole spin) was reported for the ASCA observation (Reynolds 1997) and for a 2009 XMM-Newton observation (Emmanoulopoulos et al 2011), but for an earlier XMM-Newton observation in 2000, Gondoin et al (2001) reported no detection of a broad Fe Kα line.…”

“…Early observations of Fairall 9 with ASCA (Reynolds 1997) and XMM-Newton (Gondoin et al 2001;Emmanoulopoulos et al 2011) lacked the high-energy coverage. Nevertheless, a broad Fe Kα line (the principal feature required for constraining black-hole spin) was reported for the ASCA observation (Reynolds 1997) and for a 2009 XMM-Newton observation (Emmanoulopoulos et al 2011), but for an earlier XMM-Newton observation in 2000, Gondoin et al (2001) reported no detection of a broad Fe Kα line. More recently, Fairall 9 was targeted by a Swift monitoring campaign and three new XMM-Newton observations, one of them simultaneous with NuSTAR (Lohfink et al 2016).…”

“…Fairall 9 is a bright, nearby (z = 0.047016) Seyfert 1 galaxy that has been the subject of several studies that attempt, using X-ray spectroscopy, to obtain robust measurements of the angular momentum, or spin, of the putative supermassive central black hole (Schmoll et al 2009;Emmanoulopoulos et al 2011;Patrick et al 2011aPatrick et al , 2011bPatrick et al , 2013Lohfink et al 2012a;Walton et al 2013;Lohfink et al 2016). According to the "no hair" theorem, black holes have only three measurable physical attributes, one of these being spin (mass and charge being the other two).…”

“…The reason why Fairall 9 has been of particular interest for black-hole spin measurements via X-ray spectroscopy is that it is a member of a subset of AGN that have been established to exhibit few or no signatures of line-of-sight absorption that could complicate modeling of the X-ray spectral features that are thought to carry signatures of black-hole spin (Gondoin et al 2001;Emmanoulopoulos et al 2011). Otherwise known as "bare Seyfert galaxies", AGN such as Fairall 9 provide a "clean" direct view of the accreting black-hole system (e.g.…”

A Deep X-Ray View of the Bare Agn Ark 120. I. Revealing the Soft X-Ray Line Emission

“…Ark 120 (or Arakelian 120) is a nearby (z = 0.032713, Osterbrock & Phillips 1977;Theureau et al 2005) and X-ray-bright ( =´- ; Patrick et al 2011;Baumgartner et al 2013) bare nucleus Seyfert 1. Along with its sister AGN, Fairall 9 (Emmanoulopoulos et al 2011;Lohfink et al 2012), it is the prototype example of a bare AGN. Indeed, it is one of the brightest and cleanest bare AGNs known, displaying neither intrinsic reddening in its IR/optical continuum nor evidence for absorption in UV and X-rays (Reynolds 1997;Crenshaw et al 1999), allowing a clear view of the innermost regions of the AGN.…”