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Constraining energy-dependent emissivity profiles of AGN inflows

Constraining energy-dependent emissivity profiles of AGN inflows
Constraining energy-dependent emissivity profiles of AGN inflows

The emissivity of the accretion flow is a key parameter affecting the shape of both the energy and v ariability po wer spectra of active galactic nuclei (AGNs). We explore the energy dependence of the power spectrum for five AGNs, across the XMM -Newton bandpass, and across the 0.01-1 mHz frequency range, finding a ubiquitous flattening of the power spectrum towards higher energies. We develop a framework to explore this behaviour and thereby extract the energy dependence of the emissivity assuming a simple disc-like geometry for the inflow. We find that the emissivity ranges from ⋊ ∼R -2 at energies around the soft excess and increases to ⋊ ∼R -4 or steeper abo v e 4-6 keV. We describe the changing emissivity index with a linear function in energy, finding the best-fitting slopes to vary between AGNs. We attempt to correlate the slope of the linear function against key AGN parameters but, as yet, the sample size is too small to confirm hints of a correlation with Eddington ratio.

X-rays: galaxies, galaxies: Seyfert, galaxies: active, methods: data analysis, methods: statistical
0035-8711
5245–5255
Ashton, D. I.
61ba753a-739a-4b1c-8725-216cb07ad31f
Middleton, M. J.
f91b89d9-fd2e-42ec-aa99-1249f08a52ad
Ashton, D. I.
61ba753a-739a-4b1c-8725-216cb07ad31f
Middleton, M. J.
f91b89d9-fd2e-42ec-aa99-1249f08a52ad

Ashton, D. I. and Middleton, M. J. (2022) Constraining energy-dependent emissivity profiles of AGN inflows. Monthly Notices of the Royal Astronomical Society, 513 (4), 5245–5255. (doi:10.1093/mnras/stac1122).

Record type: Article

Abstract

The emissivity of the accretion flow is a key parameter affecting the shape of both the energy and v ariability po wer spectra of active galactic nuclei (AGNs). We explore the energy dependence of the power spectrum for five AGNs, across the XMM -Newton bandpass, and across the 0.01-1 mHz frequency range, finding a ubiquitous flattening of the power spectrum towards higher energies. We develop a framework to explore this behaviour and thereby extract the energy dependence of the emissivity assuming a simple disc-like geometry for the inflow. We find that the emissivity ranges from ⋊ ∼R -2 at energies around the soft excess and increases to ⋊ ∼R -4 or steeper abo v e 4-6 keV. We describe the changing emissivity index with a linear function in energy, finding the best-fitting slopes to vary between AGNs. We attempt to correlate the slope of the linear function against key AGN parameters but, as yet, the sample size is too small to confirm hints of a correlation with Eddington ratio.

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2204.10346v1 - Accepted Manuscript
Available under License Creative Commons Attribution.
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More information

Accepted/In Press date: 14 April 2022
Published date: 1 July 2022
Additional Information: Publisher Copyright: © 2022 The Author(s).
Keywords: X-rays: galaxies, galaxies: Seyfert, galaxies: active, methods: data analysis, methods: statistical

Identifiers

Local EPrints ID: 457724
URI: http://eprints.soton.ac.uk/id/eprint/457724
ISSN: 0035-8711
PURE UUID: b9b69985-67c6-44f5-b541-6b20ac1d6498

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Date deposited: 16 Jun 2022 00:24
Last modified: 01 Feb 2023 17:39

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Contributors

Author: D. I. Ashton
Author: M. J. Middleton

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