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Lookup NU author(s): Dr Adam IngramORCiD
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© 2022 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. We show that X-ray reverberation mapping can be used to measure the distance to type 1 active galactic nuclei (AGNs). This is because X-ray photons originally emitted from the 'corona' close to the black hole irradiate the accretion disc and are reemitted with a characteristic 'reflection' spectrum that includes a prominent 6.4 keV iron emission line. The shape of the reflection spectrum depends on the irradiating flux, and the light-crossing delay between continuum photons observed directly from the corona and the reflected photons constrain the size of the disc. Siltaneously modelling the X-ray spectrum and the time delays between photons of different energies therefore constrains the intrinsic reflected luminosity, and the distance follows from the observed reflected flux. Alternatively, the distance can be measured from the X-ray spectrum alone if the black hole mass is known. We develop a new model of our reltrans X-ray reverberation mapping package, called rtdist, that has distance as a model parameter. We silate a synthetic observation that we fit with our new model, and find that this technique applied to a sample of 25 AGNs can be used to measure the Hubble constant with a 3σ statistical uncertainty of ${sim} 6,{km},{s}{-1}, {Mpc}{-1}$. Since the technique is completely independent of the traditional distance ladder and the cosmic microwave background radiation, it has the potential to address the current tension between them. We discuss sources of modelling uncertainty, and how they can be addressed in the near future.
Author(s): Ingram A, Mastroserio G, Van Der Klis M, Nathan E, Connors R, Dauser T, Garcia JA, Kara E, Konig O, Lucchini M, Wang J
Publication type: Article
Publication status: Published
Journal: Monthly Notices of the Royal Astronomical Society
Year: 2022
Volume: 509
Issue: 1
Pages: 619-633
Print publication date: 01/01/2022
Online publication date: 18/10/2021
Acceptance date: 08/10/2021
ISSN (print): 0035-8711
ISSN (electronic): 1365-2966
Publisher: Oxford University Press
URL: https://doi.org/10.1093/mnras/stab2950
DOI: 10.1093/mnras/stab2950
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