Suzaku observations of 'bare' active galactic nuclei

By D. Walton, E. Nardini, A. C. Fabian, L. Gallo, R. Reis. 2012

226 citations recorded by the source corpus.

We present an X-ray spectral analysis of a large sample of 25 ‘bare’ active galactic nuclei (AGN), sources with little or no complicating intrinsic absorption, observed with Suzaku. Our work focuses on studying the potential contribution from relativistic disc reflection and examining the implications of this interpretation for the intrinsic spectral complexities frequently displayed by AGN in the X-ray bandpass. During the analysis, we take the unique approach of attempting to simultaneously undertake a systematic analysis of the whole sample, as well as a detailed treatment of each individual source, and find that disc reflection has the required flexibility to successfully reproduce the broad-band spectrum observed for all of the sources considered. Where possible, we use the reflected emission to place constraints on the black hole spin for this sample of sources. Our analysis suggests a general preference for rapidly rotating black holes, which if taken at face value is most consistent with the scenario in which supermassive black hole growth is dominated by prolonged, ordered accretion. However, there may be observational biases towards AGN with high spin in the compiled sample, limiting our ability to draw strong conclusions for the general population at this stage. Finally, contrary to popular belief, our analysis also implies that the dichotomy between radio-loud/radio-quiet AGN is not solely related to black hole spin.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/d2d9d6fb0884146c59fb07b46079d71c3d9a6340

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In Astronomy and Astrophysics

Citations in the corpus

The role of the reflection fraction in constraining black hole spin (2014, background): “Recently, Walton et al. (2013) presented a study of 25“bare AGN” (with no evidence for warm absorbers or any other intervening material), providing perhaps the first consistent estimate for the strength of the ionized reflection (rather than the distant, neutral reflection) in a large sample of AGN.”
Normalizing a Relativistic Model of X-ray Reflection: The Definition of the Reflection Fraction and its Implementation in relxill (2016, background): “…reflection is commonly observed in both AGNs (see, e.g., Wilms et al. 2001; Fabian et al. 2004; Dauser et al. 2012; Risaliti et al. 2013; Walton et al. 2013), and in Galactic black holes such as Cyg X-1 (see, e.g., Fabian et al. 1989; Duro et al. 2011; Tomsick et al. 2014; Parker et al.…”
PS1-10jh: THE DISRUPTION OF A MAIN-SEQUENCE STAR OF NEAR-SOLAR COMPOSITION (2013, background): “However, as there are many non-thermal AGN whose spectra are more representative of bare slim-disk models (Walton et al. 2013), it remains unclear how the size of this reprocessing zone and its fractional coverage are set.”
Growing supermassive black holes in the late stages of galaxy mergers are heavily obscured (2017, result): “A recent study carried out by Oda et al. (2016), who studied in detail observations of this object carried out by Chandra, XMM-Newton, Suzaku and NuSTAR, confirmed the CT obscuration of the source (NH = 1.32 +0.32 −0.37 × 10 24 cm−2).”
IMPROVED REFLECTION MODELS OF BLACK HOLE ACCRETION DISKS: TREATING THE ANGULAR DISTRIBUTION OF X-RAYS (2013, methodology): “Furthermore, an isotropic distribution or a particular limb-darkening law is often chosen (e.g. Chiang et al. 2012; Walton et al. 2013), despite the fact that radiative transfer calculations predict an emission excess near grazing angles (known as limb brightening, e.g., Różańska & Madej 2008;…”
Measuring Black Hole Spin Using X-Ray Reflection Spectroscopy (2013, background): “…SMBH Spin Measurements The past couple of years has seen an explosion in the number of published SMBH spin measurements based on relativistic reflection spectra, including two major works that use the public data archives to compile samples of SMBH spins (Patrick et al. 2012; Walton et al. 2013).”