Accretion History of AGNs. II. Constraints on AGN Spectral Parameters Using the Cosmic X-Ray Background

Ananna T.T.; Treister E.; Urry C.M.; Ricci C.; Hickox R.C.; Padmanabhan N.; Marchesi S.; Kirkpatrick A.

Abstract

We constrain X-ray spectral shapes for the ensemble of active galactic nuclei (AGNs) based on the shape of the cosmic X-ray background (CXB). Specifically, we rule out regions of X-ray spectral parameter space that do not reproduce the CXB in the energy range 1-100 keV. The key X-ray spectral parameters are the photon index, Gamma; the cutoff energy, E-cutoff; and the reflection scaling factor, R. Assuming each parameter follows a Gaussian distribution, we first explore the parameter space using a Bayesian approach and a fixed X-ray luminosity function (XLF). For sigma(E) = 36 keV and sigma(R) = 0.14, fixed at the observed values from the Swift-BAT 70-month sample, we allow sigma(Gamma) = 0.1-0.5. In an alternative approach, we define the parameter distributions, then forward model to fit the CXB by perturbing the XLF using a neural network. This approach allows us to rule out parameter combinations that cannot reproduce the CXB for any XLF. The marginalized conditional probabilities for the four free parameters are:

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Título según WOS: Accretion History of AGNs. II. Constraints on AGN Spectral Parameters Using the Cosmic X-Ray Background
Título según SCOPUS: Accretion History of agns. II. Constraints on AGN Spectral Parameters Using the Cosmic X-Ray Background
Título de la Revista: ASTROPHYSICAL JOURNAL
Volumen: 889
Número: 1
Editorial: IOP PUBLISHING LTD
Fecha de publicación: 2020
Idioma: English
DOI:

10.3847/1538-4357/ab5aef

Notas: ISI, SCOPUS