No Signatures of Black-Hole Spin in the X-ray Spectrum of the Seyfert 1 Galaxy Fairall 9

Abstract

Fairall 9 is one of several type 1 active galactic nuclei for which it has been claimed that the angular momentum (or spin) of the supermassive black hole can be robustly measured, using the Fe K$\alpha$ emission line and Compton-reflection continuum in the X-ray spectrum. The method rests upon the interpretation of the Fe K$\alpha$ line profile and associated Compton-reflection continuum in terms of relativistic broadening in the strong gravity regime in the innermost regions of an accretion disc, within a few gravitational radii of the black hole. Here, we re-examine a Suzaku X-ray spectrum of Fairall 9 and show that a face-on toroidal X-ray reprocessor model involving only nonrelativistic and mundane physics provides an excellent fit to the data. The Fe K$\alpha$ line emission and Compton reflection continuum are calculated self-consistently, the iron abundance is solar, and an equatorial column density of $\sim 10^{24}\mathrm{c}{\mathrm{m}}^{-2}$ is inferred. In this scenario, neither the Fe K$\alpha$ line, nor the Compton-reflection continuum provide any information on the black-hole spin. Whereas previous analyses have assumed an infinite column density for the distant-matter reprocessor, the shape of the reflection spectrum from matter with a finite column density eliminates the need for a relativistically broadened Fe K$\alpha$ line. We find a 90 per cent confidence range in the Fe K$\alpha$ line FWHM of $1895$-$6205\mathrm{km}{\mathrm{s}}^{-1}$, corresponding to a distance of $\sim 3100$ to $33,380$ gravitational radii from the black hole, or $0.015$-$0.49$ pc for a black-hole mass of $\sim 1-3\times 10^8{M}_{\odot }$.

21 pages, 2 tables, 6 figures, accepted by MNRAS. arXiv admin note: text overlap with arXiv:1508.07685

References in corpus (14)

• An XMM-Newton survey of broad iron lines in Seyfert galaxies
• Constraining Black Hole Spin Via X-ray Spectroscopy
• The AGN Black Hole Mass Database
• An absorption origin for the X-ray spectral variability of MCG-6-30-15
• Study on X-ray Spectra of Obscured AGNs based on Monte Carlo simulation - an interpretation of observed wide-band spectra
• On the origin of the Fe K-alpha line cores in Active Galactic Nuclei
• Iron K$\alpha$ emission in type-I and type-II Active Galactic Nuclei
• Suzaku observations of Mrk 335: Confronting partial covering and relativistic reflection
• An absorption origin for the soft excess in Seyfert 1 AGN
• An X-ray spectral model for clumpy tori in active galactic nuclei
• What is the origin of the soft excess in AGN?
• Modeling the Fe K Line Profiles in Type I AGN with a Compton-Thick Disk Wind
• Delving Into X-ray Obscuration of Type 2 AGN, Near and Far
• A direct comparison of X-ray spectral models for tori in active galactic nuclei

Cited by in corpus (5)

• The flaring X-ray corona in the quasar PDS 456
• A Comparison of Two Methods for Estimating Black Hole Spin in Active Galactic Nuclei
• An X-ray spectral study of the origin of reflection features in bare Seyfert 1 galaxy ESO 511--G030
• Reflection features in the X-ray spectrum of Fairall 9 and implications for tests of general relativity
• The Origin of The Soft X-Ray Excess in the Seyfert 1.5 Galaxy ESO 362-G18