The iron line in MCG—6-30-15 from XMM—Newton: evidence for gravitational light bending?

By A. C. Fabian, S. Vaughan. 2003

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The lack of variability of the broad iron line seen in the Seyfert 1 galaxy MCG‐6-30-15 is studied using the EPIC pn data obtained from a 2001 observation of 325 ks, during which the count rate from the source varied by a factor of 5. The spectrum of 80 ks of data from when the source was bright, using the lowest 10 ks as background, is well fitted over the 3‐10 keV band with a simple power law of photon index � = 2.11. The source spectrum can therefore be decomposed into an approximately constant component, containing a strong iron emission line, and a variable power law component. Assuming that the power-law continuum extends down to 0.5 keV enables us to deduce the absorption acting on the nucleus. A simple model involving Galactic absorption and two photoelectric edges (at 0.72 and 0.86 keV) is adequate for the EPIC spectrum above 1 keV. It still gives a fair representation of the spectrum at lower energies where absorption lines, Unresolved Transition Arrays (UTAs), etc. are expected. Applying the absorption model to the low flux spectrum enables us to characterize it as reflection-dominated with iron about three times Solar. Fitting this model, with an additional power-law continuum,

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

The Hard X-Ray Spectrum as a Probe for Black Hole Growth in Radio-Quiet Active Galactic Nuclei (2008, background): “The apparently non-physicalR values we obtain for PG 1247+267 and PG 1634+706 (i.e.,Ω > 4π steradians) may be due to the effects of general relativistic light bending (e.g., Fabian et al. 2002; Fabian & Vaughan 2003).”
Irradiation of an accretion disc by a jet: general properties and implications for spin measurements of black holes (2013, background): “As shown by Martocchia, Matt & Karas (2002), Fabian & Vaughan (2003), Miniutti et al. (2003), and Vaughan & Fabian (2004) for the case of MCG−6-30-15, in a geometry in which the illuminating continuum is assumed to be emitted from a source on the rotational axis at heighth above the black hole,…”
Understanding X‐ray reflection emissivity profiles in AGN: locating the X‐ray source (2012, background): “Weaker variation of the reflection component that is uncorrelated with the variation in the primary continuum was observed by Vaughan & Edelson (2001) and Fabian & Vaughan (2003) in MCG–6-30-15.”
A long hard look at MCG–6-30-15 with XMM-Newton (2002, methodology): “As discussed in Fabian & Vaughan (2003), under the assumption that the total spectrum can be accurately described (on average)by the superposition of two emission components, one variable andone not (both modified by absorption), the difference spectrum will give the spectrum of only the variable…”
The role of the reflection fraction in constraining black hole spin (2014, background): “…reflection features are found in a large number of active galactic nuclei (AGN), such as, e.g., MCG−630-15 (Tanaka et al. 1995; Wilms et al. 2001; Fabian & Vaughan 2003; Marinucci et al. 2014), 1H0707−495 (Fabian et al. 2009; Dauser et al. 2012), or NGC 1365, (Risaliti et al. 2013), Galactic…”
Broad Iron-Kα Emission Lines as a Diagnostic of Black Hole Spin (2007, methodology): “Observational support for just such a geometry has emerged from detailed studies of iron line and reflection bump variability by XMM-Newton (Fabian & Vaughan 2003; Miniutti & Fabian 2004) and Suzaku (Miniutti et al. 2007).”
The lack of variability of the iron line in MCG–6‐30‐15: general relativistic effects (2003, methodology): “…would conclude that the line is almost constant both in flux and in spectral shape while the PLC varies in normalisation, as it seems to be the case in the recent XMM-Newton observation of MCG–6-30-15 (Fabian et al. 2002) that was used to study the source variability (Fabian & Vaughan 2003).”
IMPROVED REFLECTION MODELS OF BLACK HOLE ACCRETION DISKS: TREATING THE ANGULAR DISTRIBUTION OF X-RAYS (2013, background): “This reflection spectrum from the inner disk region carries information on the physical composition and condition of the matter in strong gravitational fields (e.g., Fabian et al. 2000; Fabian & Vaughan 2003; Reynolds & Nowak 2003; Dovčiak et al. 2004; Miller et al. 2008).”
An absorption origin for the X-ray spectral variability of MCG-6-30-15 (2008, methodology): “…continuum coupled with distortions of photon geodesics near the black hole, rather than by rest-frame intensity variations, so that the reflected emission appears more constant than the primary continuum seen by the observer (Fabian & Vaughan, 2003; Miniutti et al., 2003; Miniutti & Fabian, 2004).”
X-RAY REFLECTED SPECTRA FROM ACCRETION DISK MODELS. III. A COMPLETE GRID OF IONIZED REFLECTION CALCULATIONS (2013, background): “…a skewed line profile with a red wing that can extend to very low energies, particularly in the case of high spin (e.g., Fabian et al. 2000; Fabian & Vaughan 2003; Reynolds & Nowak 2003; Dovčiak et al. 2004; Miller et al. 2008; Steiner et al. 2011; Reynolds et al. 2012; Dauser et al.…”
Broad iron L line and X-ray reverberation in 1H0707-495 (2009, background): “Unlike other well-studied AGN (e.g. MCG-6-30-15 and Mrk 766), the spectrum of 1H0707 does not show any signs of warm absorption, giving an uninterrupted view to the inner regions of the accretion system.”
Suzaku Observations of the Hard X-ray Variability of MCG-6-30-15: the Effects of Strong Gravity Around a Kerr Black Hole (2006, background): “This can disconnect variations in the continuum from those of the reflection and has led to the development of the light-bending model (Fabian & Vaughan 2003; Miniutti et al 2003, 2004), which is a generalization of earlier work on the strong field regime (Martocchia & Matt 1996; Reynolds &…”
A light bending model for the X-ray temporal and spectral properties of accreting black holes (2003, methodology): “Variations in the height of the primary source above the accretion disc produce the bulk of the variability of both the observed continuum and the reflection component (Martocchia, Matt & Karas 2002; Fabian & Vaughan 2003).”
An Extended Scheme for Fitting X-Ray Data with Accretion Disk Spectra in the Strong Gravity Regime (2004, background): “The puzzling stability of this line has been attributed, amongst other things, to general relativity effects very close to the black hole (Miniutti et al. 2003; Fabian & Vaughan 2003).”