X-ray selection of Compton Thick AGN at high redshift

Abstract

Compton Thick (CT) AGN are a key ingredient of Cosmic X-ray Background (CXB) synthesis models, but are still an elusive component of the AGN population beyond the local Universe. Multi-wavelength surveys are the only way to find them at z > 0.1, and a deep X-ray coverage is crucial in order to clearly identify them among star forming galaxies. As an example, the deep and wide COSMOS survey allowed us to select a total of 34 CT sources. This number is computed from the 64 nominal CT candidates, each counted for its N H probability distribution function. For each of these sources, rich multi-wavelength information is available, and is used to confirm their obscured nature, by comparing the expected AGN luminosity from spectral energy distribution fitting, with the absorption-corrected X-ray luminosity. While Chandra is more efficient, for a given exposure, in detecting CT candidates in current surveys (by a factor ~2), deep XMM-Newton pointings of bright sources are vital to fully characterize their properties: NH distribution above 10^25 cm^-2, reflection intensity etc., all crucial parameters of CXB models. Since luminous CT AGN at high redshift are extremely rare, the future of CT studies at high redshift will have to rely on the large area surveys currently underway, such as XMM-XXL and Stripe82, and will then require dedicated follow-up with XMM-Newton, while waiting for the advent of the ESA mission Athena.

6 pages, 7 figures, to appear in Astronomische Nachrichten, presented at the XMM-Newton: The Next Decade conference, ESAC, Madrid, Spain, 9 - 11 May 2016

References in corpus (22)

• The Cosmic Evolution Survey (COSMOS) -- Overview
• COSMOS Photometric Redshifts with 30-bands for 2-deg2
• The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
• 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
• The Chandra COSMOS Legacy survey: overview and point source catalog
• The Chandra COSMOS Survey, I: Overview and Point Source Catalog
• X-ray spectral properties of AGN in the Chandra Deep Field South
• The XMM-Newton wide-field survey in the COSMOS field: I. Survey description
• The Chandra COSMOS Legacy survey: optical/IR identifications
• Obscuration-dependent evolution of Active Galactic Nuclei
• The XMM-Newton wide-field survey in the COSMOS field. The point-like X-ray source catalogue
• The XXL Survey: I. Scientific motivations - XMM-Newton observing plan - Follow-up observations and simulation programme
• Unveiling obscured accretion in the Chandra Deep Field South
• The X-Ray to Mid-Infrared Relation of AGN at High Luminosity
• The Hard X-Ray Luminosity Function of High-Redshift ($3<z\lesssim 5$) Active Galactic Nuclei
• Compton Thick AGN in the XMM-COSMOS survey
• Mapping the average AGN accretion rate in the SFR-M* plane for Herschel selected galaxies at 0<z<2.5
• Revealing X-ray obscured quasars in SWIRE sources with extreme mid-IR/optical flux ratios
• The NuSTAR Extragalactic Surveys: Overview and Catalog from the COSMOS Field
• Mass without radiation: heavily obscured AGN, the X-ray Background and the Black Hole Mass Density
• The quest for Type 2 quasars: Chandra observations of luminous obscured quasars in the Sloan Digital Sky Survey
• The space density of Compton-thick AGN at z~0.8 in the zCOSMOS-Bright Survey

Cited by in corpus (1)

• Multi-wavelength Selected Compton-thick AGNs in Chandra Deep Field-South Survey