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The NuSTAR Extragalactic Surveys: Unveiling Rare, Buried AGNs and Detecting the Contributors to the Peak of the Cosmic X-Ray Background

Masini, A. and Comastri, A. and Civano, F. and Hickox, R. C. and Carroll, C. M. and Suh, H. and Brandt, W. N. and DiPompeo, M. A. and Harrison, F. A. and Stern, D. (2018) The NuSTAR Extragalactic Surveys: Unveiling Rare, Buried AGNs and Detecting the Contributors to the Peak of the Cosmic X-Ray Background. Astrophysical Journal, 867 (2). Art. No. 162. ISSN 1538-4357.

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We report on the results of active galactic nuclei (AGNs) detection by NuSTAR performed in three extragalactic survey fields (COSMic Evolutionary Survey field (COSMOS), Ultra Deep Survey (UDS), and Extended Chandra Deep Field-South (ECDFS)) in three hard bands, namely H1 (8–16 keV), H2 (16–24 keV), and VH (35–55 keV). The aggregated area of the surveys is ~2.7 deg^2. While a large number of sources is detected in the H1 band (72 at the 97% level of reliability), the H2 band directly probing close to the peak of the Cosmic X-ray Background (CXB) returns four significant detections, and two tentative (although not significant) detections are found in the VH-band. All of the sources detected above 16 keV are also detected at lower energies. We compute the integral number counts for sources in such bands, which show broad consistency with population-synthesis models of the CXB. We furthermore identify two Compton-thick AGNs, one in the COSMOS field, associated with a hard and faint Chandra source, and one in the UDS field, never detected in the X-ray band before. Both sources are at the same redshift z ~ 1.25, which shifts their Compton-hump into the H1 band, and were previously missed in the usually employed NuSTAR bands, confirming the potential for using the H1 band to discover obscured AGNs at z > 1 in deep surveys.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Masini, A.0000-0002-7100-9366
Comastri, A.0000-0003-3451-9970
Civano, F.0000-0002-2115-1137
Hickox, R. C.0000-0003-1468-9526
Carroll, C. M.0000-0003-3574-2963
Suh, H.0000-0002-2536-1633
Brandt, W. N.0000-0002-0167-2453
DiPompeo, M. A.0000-0001-6788-1701
Harrison, F. A.0000-0003-2992-8024
Stern, D.0000-0003-2686-9241
Additional Information:© 2018. The American Astronomical Society. Received 2018 July 20; revised 2018 August 31; accepted 2018 September 27; published 2018 November 12. We thank the anonymous referee, whose comments helped improve the quality and clarity of the paper. This work was supported under NASA Contract NNG08FD60C, and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. This research made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). This research has also made use of data obtained from the Chandra Data Archive and the Chandra Source Catalog, and software provided by the Chandra X-ray Center (CXC). Figure 4 is partially based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under ESO programme ID 179.A-2005 and on data products produced by TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium. The DEIMOS spectrum presented herein was obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013; The Astropy Collaboration et al. 2018), and XSPEC (Arnaud 1996). A.M. and A.C. acknowledge support from the ASI/INAF grant I/037/12/0011/13. R.C.H. acknowledges support from the National Science Foundation through CAREER award 1554584, and from NASA through grant number NNX15AP24G. W.N.B. acknowledges support from Caltech NuSTAR subcontract 44A-1092750. Facilities: NuSTAR - The NuSTAR (Nuclear Spectroscopic Telescope Array) mission, Chandra - . Software: NuSTARDAS, FTOOLS.
Group:Space Radiation Laboratory, NuSTAR, Astronomy Department
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Agenzia Spaziale Italiana (ASI)I/037/12/0011/13
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Caltech NuSTAR subcontract44A-1092750
Subject Keywords:galaxies: active; galaxies: Seyfert
Issue or Number:2
Record Number:CaltechAUTHORS:20181113-112609358
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Official Citation:A. Masini et al 2018 ApJ 867 162
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90865
Deposited By: George Porter
Deposited On:14 Nov 2018 00:31
Last Modified:03 Oct 2019 20:29

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