Fitting the spectrum of the X-ray background: the effects of high metallicity absorption

Abstract

Recent work by Risaliti et al.(1999) suggests that more than half of all Seyfert 2 galaxies in the local universe are Compton-thick (N_H > 10^24 cm^-2). This has implications for AGN synthesis models for the X-ray background (XRB), the flexibility of which for the inclusion of large numbers of high-z type 2 sources we examine here. We highlight the importance of Compton down-scattering in determining the individual source spectra and the fit to the XRB spectrum, and demonstrate how parameter space opens up considerably if a super-solar iron abundance is assumed for the absorbing material. This is illustrated with a model which satisfies the present constraints, but which predicts substantial numbers of type 2 source at the faint flux levels soon to be probed for the first time by the Chandra and XMM missions. We demonstrate also how a strong negative K-correction facilitates the detection of sources with 10^~24 < N_H < 10^25 cm^-2 out to the highest redshifts at which they could plausibly exist.

7 pages, 11 figures; to appear in MNRAS

References in corpus (4)

• A 3 dimensional diagnostic diagram for Seyfert 2s: probing X-ray absorption and Compton thickness
• The mass density in black holes inferred from the X-ray background
• Log N - Log S Relations and Spectral Properties of Sources from the ASCA Large Sky Survey --- their Implications for the Origin of the Cosmic X-ray Background (CXB)
• The contribution of AGN to the X-ray background: the effect of iron features

Cited by in corpus (43)

• Cosmological Evolution of the Hard X-ray AGN Luminosity Function and the Origin of the Hard X-ray Background
• Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-Thick Populations
• Self-Consistent Models of the AGN and Black Hole Populations: Duty Cycles, Accretion Rates, and the Mean Radiative Efficiency
• Resolving the mid-infrared cores of local Seyferts
• A synthesis model for AGN evolution: supermassive black holes growth and feedback modes
• The Nature of the Hard X-ray Background Sources: Optical, Near-infrared, Submillimeter, and Radio Properties
• Suzaku Observations of Active Galactic Nuclei Detected in the Swift/BAT Survey: Discovery of "New Type" of Buried Supermassive Black Holes
• Compton Thick AGN: the dark side of the X-ray background
• Study on X-ray Spectra of Obscured AGNs based on Monte Carlo simulation - an interpretation of observed wide-band spectra
• Testing the connection between the X-ray and submillimetre source populations using Chandra
• The HELLAS2XMM survey: VI. X-ray absorption in the 1dfAGN sample through a spectral analysis
• A population of high-redshift type-2 quasars-I. Selection Criteria and Optical Spectra
• The BeppoSAX High Energy Large Area Survey HELLAS, III: testing synthesis models for the X-ray background
• The accretion history of the Universe with the SKA
• Revealing the heavily obscured AGN population of High Redshift 3CRR Sources with Chandra X-ray Observations
• X-ray background synthesis: the infrared connection
• The effects of a comptonizing corona on the appearance of the reflection components in accreting black hole spectra
• Extremely red galaxy counterparts to 7C radio sources
• On the faint end of the high redshift AGN luminosity function
• An XMM-Newton Study of the Hard X-ray Sky
• Unveiling the nature of the highly obscured AGN in NGC5643 with XMM-Newton
• Chandra detection of reflected X-ray emission from the type 2 QSO in IRAS 09104+4109
• Evidence for a large fraction of Compton-thick quasars at high redshift
• X-Ray Evolution of Active Galactic Nuclei and Hierarchical Galaxy Formation
• Constraints on light bending and reflection from the hard X-ray background
• On the detectability of distant Compton-thick obscured quasars
• XMM-Newton observations of two hyperluminous IRAS galaxies: Compton-thick quasars with obscuring starbursts
• The X-ray background and the deep X-ray surveys
• Multi-wavelength observations of serendipitous Chandra X-ray sources in the field of A2390
• Infrared observations of serendipitous hard Chandra X-ray sources
• Discovery of a z=4.93, X-ray selected quasar by the Chandra Multiwavelength Project (ChamP)
• A medium deep Chandra and Subaru survey of the 13hr XMM/ROSAT deep survey area
• NuSTAR and Keck Observations of Heavily Obscured Quasars Selected by WISE
• Hot dust in two hard Chandra X-ray sources
• The preferentially magnified active nucleus in IRAS F10214+4724 - III. VLBI observations of the radio core
• A physical model for the hard X-ray background
• The discovery of a type-II quasar at z = 1.65 with integral-field spectroscopy
• A New Sample of Obscured AGNs Selected from the XMM-Newton and AKARI Surveys
• Constraining Torus Models for AGNs Using X-Ray Observations
• The Compton-thick quasar at the heart of the high-redshift giant radio galaxy 6C 0905+39
• A Novel Machine Learning Approach to Disentangle Multi-Temperature Regions in Galaxy Clusters
• Optical and near-infrared observations of hard serendipitous Chandra sources
• X-Ray bright optically faint active galactic nuclei in the Subaru Hyper Suprime-Cam wide survey