High Density Reflection Spectroscopy – II. The density of the inner black hole accretion disc in AGN

Jiang, Jiachen; Fabian, A. C.; Dauser, Robert C.; Gallo, Luigi; García, Javier A.; Kara, Erin; Parker, M. L.; Tomsick, John A.; Walton, D. J.; Reynolds, C. S.

doi:10.1093/mnras/stz2326

Cited by 109 publications

(132 citation statements)

References 76 publications

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“…Accretion disc density has recently been shown to be anticorrelated with M BH , with low-mass systems such as NLS1s more frequently exhibiting log N > 15 cm −3 (Jiang et al 2019). We first tested for the possibility of non-solar iron abundance in our data by allowing A Fe to be free to vary, finding a best-fitting value consistent with a solar abundance while not providing a significant fit improvement.…”

Section: Modelling the Broad-band Continuummentioning

confidence: 99%

Characterizing continuum variability in the radio-loud narrow-line Seyfert 1 galaxy IRAS 17020+4544

Gonzalez

Gallo

Kosec

et al. 2020

Monthly Notices of the Royal Astronomical Society

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ABSTRACT We present results of temporal and spectral analyses on four XMM–Newton EPIC pn observations of IRAS 17020+4544, a narrow-line Seyfert 1 galaxy with evidence of a radio jet. Analysis of the light curves reveals that this radio-loud source does not behave like the bulk population of its radio-quiet counterparts. A trend of spectral hardening with increased flux is found. Variability is found to increase with energy, though it decreases as the spectrum hardens. The first 40 ks of the most recent observation behave uniquely among the epochs, exhibiting a softer spectral state than at any other time. Possible non-stationarity at low energies is found, with no such effect present at higher energies, suggesting at least two distinct spectral components. A reverberation signature is confirmed, with the lag-frequency, lag-energy, and covariance spectra changing significantly during the soft-state epoch. The temporal analysis suggests a variable power law in the presence of a reflection component, thus motivating such a fit for the 0.3−10 keV EPIC pn spectra from all epochs. We find an acceptable spectral fit using the timing-motivated parameters and report the detection of a broad Fe K emission line, requiring an additional model component beyond the reflection spectrum. We discuss links between this source and other narrow-line Seyfert 1 sources that show evidence of jet activity, finding similarities among this currently very limited sample of interesting objects.

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Section: Modelling the Broad-band Continuummentioning

confidence: 99%

Characterizing continuum variability in the radio-loud narrow-line Seyfert 1 galaxy IRAS 17020+4544

Gonzalez

Gallo

Kosec

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Spectral fitting results using the warm corona hypothesis find that the heated layer has τ T ≈ 10-20 (e.g., Petrucci et al 2018). In addition, the heating and cooling processes in the gas (e.g., Compton scattering, bremsstrahlung) are strong functions of density, so the spectra produced by the models will depend on the assumed density of the slab (e.g., Ballantyne 2004;García et al 2016;Jiang et al 2019a). Therefore, the following set of four scenarios are considered to explore the properties of a warm corona: n H = 2 × 10 14 cm −3 (τ T = 10, 20) and n H = 5 × 10 14 cm −3 (τ T = 10, 20).…”

Section: Calculationsmentioning

confidence: 99%

Examining the physical conditions of a warm corona in active galactic nuclei accretion discs

Ballantyne

2019

Monthly Notices of the Royal Astronomical Society

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A warm corona at the surface of an accretion disc has been proposed as a potential location for producing the soft excess commonly observed in the X-ray spectra of active galactic nuclei (AGNs). In order to fit the observed data the gas must be at temperatures of ∼ 1 keV and have an optical depth of τ T ≈ 10-20. We present one-dimensional calculations of the physical conditions and emitted spectra of a τ T = 10 or 20 gas layer subject to illumination from an X-ray power-law (from above), a blackbody (from below) and a variable amount of internal heating. The models show that a warm corona with kT ∼ 1 keV can develop, producing a strong Comptonized soft excess, but only if the internal heating flux is within a relatively narrow range. Similarly, if the gas density of the layer is too large then efficient cooling will stop a warm corona from forming. The radiation from the hard X-ray power-law is crucial in producing a warm corona, indicating that a warm and hot corona may co-exist in AGN accretion discs, and their combined effect leads to the observed soft excess. Intense heating of a warm corona leads to steep X-ray spectra with ionised Fe Kα lines, similar to those seen in some narrow-line Seyfert 1 galaxies.An alternative model for the soft excess returns to the idea of direct emission from the AGN accretion disc, but now proposes

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“…Higher disk densities lead to a strong excess of the reflected continuum at soft energies due to the enhancement of free-free heating in the atmosphere of the disk, which increases with rising density (Ballantyne 2004;García et al 2016). An extended study of 17 AGN characterized by a strong soft excess have made use of high-density reflection models to reproduce their X-ray spectra (Jiang et al 2019b), finding tentative correlations between the black-hole mass, accretion rate, and accretion-disk density.…”

Section: Discussionmentioning

confidence: 99%

Plasma-environment effects on K lines of astrophysical interest

Deprince

Bautista

Fritzsche

et al. 2020

A&A

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Aims. In the context of black-hole accretion disks, we aim to compute the plasma-environment effects on the atomic parameters used to model the decay of K-vacancy states in moderately charged iron ions, namely Fe IX – Fe XVI. Methods. We used the fully relativistic multiconfiguration Dirac–Fock method approximating the plasma electron–nucleus and electron–electron screenings with a time-averaged Debye–Hückel potential. Results. We report modified ionization potentials, K-threshold energies, wavelengths, radiative emission rates, and Auger widths for plasmas characterized by electron temperatures and densities in the ranges 105−107 K and 1018−1022 cm−3. Conclusions. This study confirms that the high-resolution X-ray spectrometers onboard the future XRISM and Athena space missions will be capable of detecting the lowering of the K edges of these ions due to the extreme plasma conditions occurring in accretion disks around compact objects.

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High Density Reflection Spectroscopy – II. The density of the inner black hole accretion disc in AGN

Cited by 109 publications

References 76 publications

Characterizing continuum variability in the radio-loud narrow-line Seyfert 1 galaxy IRAS 17020+4544

Characterizing continuum variability in the radio-loud narrow-line Seyfert 1 galaxy IRAS 17020+4544

Examining the physical conditions of a warm corona in active galactic nuclei accretion discs

Plasma-environment effects on K lines of astrophysical interest

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