| Title | Accretion History of AGNs. II. Constraints on AGN Spectral Parameters Using the Cosmic X-Ray Background |
| Authors | Ananna, Tonima Tasnim Treister, Ezequiel Urry, C. Megan Ricci, C. Hickox, Ryan C. Padmanabhan, Nikhil Marchesi, Stefano Kirkpatrick, Allison |
| Affiliation | Dartmouth Coll, Dept Phys & Astron, 6127 Wilder Lab, Hanover, NH 03755 USA Yale Univ, Dept Phys, POB 201820, New Haven, CT 06520 USA Yale Ctr Astron & Astrophys, POB 208120, New Haven, CT 06520 USA Pontificia Univ Catolica Chile, Fac Fis, Inst Astrofis, Casilla 306, Santiago 22, Chile Yale Univ, Dept Astron, POB 208101, New Haven, CT 06520 USA Peking Univ, Kavli Inst Astron & Astrophys, Beijing 100871, Peoples R China INAF Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy Clemson Univ, Dept Phys & Astron, Kinard Lab Phys, Clemson, SC 29634 USA Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA |
| Keywords | ACTIVE GALACTIC NUCLEUS COSMOLOGICAL EVOLUTION LUMINOSITY FUNCTION COMPTON REFLECTION BROAD-BAND CHANDRA ORIGIN |
| Issue Date | 20-Jan-2020 |
| Publisher | ASTROPHYSICAL JOURNAL |
| 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: |
| URI | http://hdl.handle.net/20.500.11897/587114 |
| ISSN | 0004-637X |
| DOI | 10.3847/1538-4357/ab5aef |
| Indexed | SCI(E) Scopus |
| Appears in Collections: | 科维理天文与天体物理研究所 |
