TY - JOUR
T1 - The NuSTAR Extragalactic Surveys
T2 - Unveiling Rare, Buried AGNs and Detecting the Contributors to the Peak of the Cosmic X-Ray Background
AU - Masini, A.
AU - Comastri, A.
AU - Civano, F.
AU - Hickox, R. C.
AU - Carroll, C. M.
AU - Suh, H.
AU - Brandt, W. N.
AU - Dipompeo, M. A.
AU - Harrison, F. A.
AU - Stern, D.
N1 - Funding Information:
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.
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved..
PY - 2018/11/10
Y1 - 2018/11/10
N2 - 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 deg2. 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.
AB - 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 deg2. 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.
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U2 - 10.3847/1538-4357/aae539
DO - 10.3847/1538-4357/aae539
M3 - Article
AN - SCOPUS:85056739781
SN - 0004-637X
VL - 867
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 162
ER -