Probing the geometry and motion of AGN coronae through accretion disc emissivity profiles

Gonzalez, A. G.; Wilkins, D. R.; Gallo, Luigi

doi:10.1093/mnras/stx2080

Cited by 57 publications

(54 citation statements)

References 32 publications

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“…This result is however not consistent with a truncated disk (R in = 2.2 +0.6 −0.3 R ISCO ). We note that this result is at least qualitatively consistent with theoretical modeling predictions that favor a much steeper emissivity profile in the inner accretion disk (Wilkins & Fabian 2011, 2012Gonzalez et al 2017).…”

Section: Fe Kα Emission Linesupporting

confidence: 89%

Broadband X-Ray Constraints on the Accreting Black Hole in Quasar 4C 74.26

Tzanavaris

Yaqoob

LaMassa

et al. 2019

ApJ

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X-ray data for quasar 4C 74.26 have previously been modeled with a broad Fe Kα emission line and reflection continuum originating in the inner part of the accretion disk around the central supermassive black hole (SMBH), i.e. the strong gravity regime. We modeled broadband X-ray spectra from Suzaku and NuSTAR with MYTORUS, self-consistently accounting for Fe Kα line emission, as well as direct and reflected continuum emission, from finite column density matter. A narrow Fe Kα emission line originating in an X-ray reprocessor with solar Fe abundance far from the central SMBH is sufficient to produce excellent fits for all spectra. For the first time, we are able to measure the global, out of the line-of-sight column density to be in the range ∼1.5 to ∼2.9 × 10 24 cm −2 , i.e. in the Compton thick regime, while the line-of-sight column density is Compton thin in all observations. The Fe Kα emission line is unresolved in all but one observations. The Compton scattered continuum from distant matter removes the need for relativistic broadening of the Fe Kα emission line, which is required for SMBH spin measurements. The resolved line observation can alternatively be modeled with a relativistic model but we do not find evidence for a truncated accretion disk model. We conclude that the X-ray emission in these 4C 74.26 data is unlikely to originate in the inner accretion disk region and thus cannot be used to measure SMBH spin.

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Section: Fe Kα Emission Linesupporting

confidence: 89%

Broadband X-Ray Constraints on the Accreting Black Hole in Quasar 4C 74.26

Tzanavaris

Yaqoob

LaMassa

et al. 2019

ApJ

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“…Therefore, with the current quality of the data, broken (or twice-broken) power laws can be used as adequate approximations of the intrinsic emissivity profiles (e.g. Wilkins & Fabian 2012;Gonzalez et al 2017).…”

Section: Lamp-post Scheme Of the Corona And Radial Emissivity Profilementioning

confidence: 99%

Steep X-ray reflection emissivity profiles in AGN as the result of radially structured disc ionization

Kammoun

Domček

Svoboda

et al. 2019

Monthly Notices of the Royal Astronomical Society

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X-ray observations suggest high compactness of coronae in active galactic nuclei as well as in X-ray binaries. The compactness of the source implies a strong radial dependence in the illumination of the accretion disc. This will, for any reasonable radial profile of the density, lead to a radial profile of the disc ionisation. Svoboda et al. (2012) showed on a single example that assuming a radially-structured ionisation profile of the disc can cause an artificial increase of the radial-emissivity parameter. We further investigate how the X-ray spectra are modified and quantify this effect for a wide range of parameters. Computations are carried out with the current state-of-the-art models for relativistic reflection. We simulated spectra using the response files of the micro-calorimeter X-IFU, which is planned to be on board of Athena. We assumed typical parameters for X-ray bright Seyfert-1 galaxies and considered two scenarios for the disc ionisation: 1) a radial profile for the disc ionisation, 2) a constant disc ionisation. We found that steep emissivity profiles can be indeed achieved due to the radial profile of the disc ionisation, which becomes more important for the cases where the corona is located at low heights above the black hole and this effect may be even more prominent than the geometrical effects. We also found that the cases with high inner disc ionisation, rapidly decreasing with radius, may result in an inaccurate black hole spin measurements.

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“…a corona or jet). Gonzalez et al (2017) performed general relativistic (GR) ray tracing simulations studying the illumination pattern of the accretion disc (i.e. emissivity profile) for various corona geometries and velocities, constructing an approximation for the reflection fraction, R, produced by point source coronae (i.e.…”

Section: The X-ray Sourcementioning

confidence: 99%

The changing source of X-ray reflection in the radio-intermediate Seyfert 1 galaxy III Zw 2

Gonzalez

Waddell

Gallo

2017

Monthly Notices of the Royal Astronomical Society

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We report on X-ray observations of the radio-intermediate, X-ray bright Seyfert 1 galaxy, III Zw 2, obtained with XMM-Newton, Suzaku, and Swift over the past 17years. The source brightness varies significantly over yearly time scales, but more modestly over periods of days. Pointed observations with XMM-Newton in 2000 and Suzaku in 2011 show spectral differences despite comparable X-ray fluxes. The Suzaku spectra are consistent with a power law continuum and a narrow Gaussian emission feature at ∼ 6.4 keV, whereas the earlier XMM-Newton spectrum requires a broader Gaussian profile and soft-excess below ∼ 2 keV. A potential interpretation is that the primary power law emission, perhaps from a jet base, preferentially illuminates the inner accretion disc in 2000, but the distant torus in 2011. The interpretation could be consistent with the hypothesised precessing radio jet in III Zw 2 that may have originated from disc instabilities due to an ongoing merging event.

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Probing the geometry and motion of AGN coronae through accretion disc emissivity profiles

Cited by 57 publications

References 32 publications

Broadband X-Ray Constraints on the Accreting Black Hole in Quasar 4C 74.26

Broadband X-Ray Constraints on the Accreting Black Hole in Quasar 4C 74.26

Steep X-ray reflection emissivity profiles in AGN as the result of radially structured disc ionization

The changing source of X-ray reflection in the radio-intermediate Seyfert 1 galaxy III Zw 2

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