The Chandra COSMOS Legacy Survey : Energy Spectrum of the Cosmic X-Ray Background and Constraints on Undetected Populations

Show simple item record Cappelluti, Nico Li, Yanxia Ricarte, Angelo Agarwal, Bhaskar Allevato, Viola Ananna, Tonima Tasnim Ajello, Marco Civano, Francesca Comastri, Andrea Elvis, Martin Finoguenov, Alexis Gilli, Roberto Hasinger, Guenther Marchesi, Stefano Natarajan, Priyamvada Pacucci, Fabio Treister, E. Urry, C. Megan 2017-06-05T07:21:02Z 2017-06-05T07:21:02Z 2017-03-01
dc.identifier.citation Cappelluti , N , Li , Y , Ricarte , A , Agarwal , B , Allevato , V , Ananna , T T , Ajello , M , Civano , F , Comastri , A , Elvis , M , Finoguenov , A , Gilli , R , Hasinger , G , Marchesi , S , Natarajan , P , Pacucci , F , Treister , E & Urry , C M 2017 , ' The Chandra COSMOS Legacy Survey : Energy Spectrum of the Cosmic X-Ray Background and Constraints on Undetected Populations ' , Astrophysical Journal , vol. 837 , no. 1 , 19 .
dc.identifier.other PURE: 85153154
dc.identifier.other PURE UUID: a495e0d9-9e8d-494d-877c-4e5a84e87453
dc.identifier.other WOS: 000401170800004
dc.identifier.other Scopus: 85015154606
dc.description.abstract Using Chandra observations in the 2.15 deg(2) COSMOS-legacy field, we present one of the most accurate measurements of the Cosmic X-ray Background (CXB) spectrum to date in the [0.3-7] keV energy band. The CXB has three distinct components: contributions from two Galactic collisional thermal plasmas at kT similar to 0.27 and 0.07 keV and an extragalactic power law with a photon spectral index Gamma = 1.45 +/- 0.02. The 1 keV normalization of the extragalactic component is 10.91 +/- 0.16 keV cm(-2) s(-1) sr(-1) keV(-1). Removing all X-ray-detected sources, the remaining unresolved CXB is best fit by a power law with normalization 4.18 +/- 0.26 keV cm(-2) s(-1) sr(-1) keV(-1) and photon spectral index Gamma = 1.57 +/- 0.10. Removing faint galaxies down to i(AB) similar to 27-28 leaves a hard spectrum with Gamma similar to 1.25 and a 1 keV normalization of similar to 1.37 keV cm(-2) s(-1) sr(-1) keV(-1). This means that similar to 91% of the observed CXB is resolved into detected X-ray sources and undetected galaxies. Unresolved sources that contribute similar to 8%-9% of the total CXB show marginal evidence of being harder and possibly more obscured than resolved sources. Another similar to 1% of the CXB can be attributed to still undetected star-forming galaxies and absorbed active galactic nuclei. According to these limits, we investigate a scenario where early black holes totally account for non-source CXB fraction and constrain some of their properties. In order to not exceed the remaining CXB and the z similar to 6 accreted mass density, such a population of black holes must grow in Compton-thick envelopes with N-H > 1.6 x 10(25) cm(-2) and form in extremely low-metallicity environments (Z(circle dot)) similar to 10(-3). en
dc.format.extent 8
dc.language.iso eng
dc.relation.ispartof Astrophysical Journal
dc.rights unspecified
dc.rights.uri info:eu-repo/semantics/openAccess
dc.subject catalogs
dc.subject infrared: diffuse background
dc.subject quasars: supermassive black holes
dc.subject surveys
dc.subject X-rays: diffuse background
dc.subject 1ST BLACK-HOLES
dc.subject XMM-NEWTON
dc.subject EVOLUTION
dc.subject ABSORPTION
dc.subject MODEL
dc.subject LUMINOSITY
dc.subject 115 Astronomy, Space science
dc.title The Chandra COSMOS Legacy Survey : Energy Spectrum of the Cosmic X-Ray Background and Constraints on Undetected Populations en
dc.type Article
dc.contributor.organization Department of Physics
dc.description.reviewstatus Peer reviewed
dc.relation.issn 0004-637X
dc.rights.accesslevel openAccess
dc.type.version publishedVersion

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