THE NuSTAR EXTRAGALACTIC SURVEYS: The NUMBER COUNTS of ACTIVE GALACTIC NUCLEI and the RESOLVED FRACTION of the COSMIC X-RAY BACKGROUND

F. A. Harrison; J. Aird; F. Civano; G. Lansbury; J. R. Mullaney; D. R. Ballantyne; D. M. Alexander; D. Stern; M. Ajello; D. Barret; F. E. Bauer; M. Baloković; W. N. Brandt; M. Brightman; S. E. Boggs; F. E. Christensen; A. Comastri; W. W. Craig; A. Del Moro; K. Forster; P. Gandhi; P. Giommi; B. W. Grefenstette; C. J. Hailey; R. C. Hickox; A. Hornstrup; T. Kitaguchi; J. Koglin; B. Luo; K. K. Madsen; P. H. Mao; H. Miyasaka; K. Mori; M. Perri; M. Pivovaroff; S. Puccetti; V. Rana; E. Treister; D. Walton; N. J. Westergaard; D. Wik; L. Zappacosta; W. W. Zhang; A. Zoglauer

doi:10.3847/0004-637X/831/2/185

THE NuSTAR EXTRAGALACTIC SURVEYS: The NUMBER COUNTS of ACTIVE GALACTIC NUCLEI and the RESOLVED FRACTION of the COSMIC X-RAY BACKGROUND

F. A. Harrison, J. Aird, F. Civano, G. Lansbury, J. R. Mullaney, D. R. Ballantyne, D. M. Alexander, D. Stern, M. Ajello, D. Barret, F. E. Bauer, M. Baloković, W. N. Brandt, M. Brightman, S. E. Boggs, F. E. Christensen, A. Comastri, W. W. Craig, A. Del Moro, K. ForsterP. Gandhi, P. Giommi, B. W. Grefenstette, C. J. Hailey, R. C. Hickox, A. Hornstrup, T. Kitaguchi, J. Koglin, B. Luo, K. K. Madsen, P. H. Mao, H. Miyasaka, K. Mori, M. Perri, M. Pivovaroff, S. Puccetti, V. Rana, E. Treister, D. Walton, N. J. Westergaard, D. Wik, L. Zappacosta, W. W. Zhang, A. Zoglauer

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Abstract

We present the 3-8 keV and 8-24 keV number counts of active galactic nuclei (AGNs) identified in the Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic surveys. NuSTAR has now resolved 33%-39% of the X-ray background in the 8-24 keV band, directly identifying AGNs with obscuring columns up to . In the softer 3-8 keV band the number counts are in general agreement with those measured by XMM-Newton and Chandra over the flux range S(3-8 keV)/ probed by NuSTAR. In the hard 8-24 keV band NuSTAR probes fluxes over the range S(8-24 keV)/, a factor ∼100 fainter than previous measurements. The 8-24 keV number counts match predictions from AGN population synthesis models, directly confirming the existence of a population of obscured and/or hard X-ray sources inferred from the shape of the integrated cosmic X-ray background. The measured NuSTAR counts lie significantly above simple extrapolation with a Euclidian slope to low flux of the Swift/BAT 15-55 keV number counts measured at higher fluxes (S(15-55 keV) 10^-11 ), reflecting the evolution of the AGN population between the Swift/BAT local () sample and NuSTAR's sample. CXB synthesis models, which account for AGN evolution, lie above the Swift/BAT measurements, suggesting that they do not fully capture the evolution of obscured AGNs at low redshifts.

Original language	English (US)
Article number	185
Journal	Astrophysical Journal
Volume	831
Issue number	2
DOIs	https://doi.org/10.3847/0004-637X/831/2/185
State	Published - Nov 10 2016

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/0004-637X/831/2/185

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Harrison, F. A., Aird, J., Civano, F., Lansbury, G., Mullaney, J. R., Ballantyne, D. R., Alexander, D. M., Stern, D., Ajello, M., Barret, D., Bauer, F. E., Baloković, M., Brandt, W. N., Brightman, M., Boggs, S. E., Christensen, F. E., Comastri, A., Craig, W. W., Del Moro, A., ... Zoglauer, A. (2016). THE NuSTAR EXTRAGALACTIC SURVEYS: The NUMBER COUNTS of ACTIVE GALACTIC NUCLEI and the RESOLVED FRACTION of the COSMIC X-RAY BACKGROUND. Astrophysical Journal, 831(2), Article 185. https://doi.org/10.3847/0004-637X/831/2/185

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title = "THE NuSTAR EXTRAGALACTIC SURVEYS: The NUMBER COUNTS of ACTIVE GALACTIC NUCLEI and the RESOLVED FRACTION of the COSMIC X-RAY BACKGROUND",

abstract = "We present the 3-8 keV and 8-24 keV number counts of active galactic nuclei (AGNs) identified in the Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic surveys. NuSTAR has now resolved 33%-39% of the X-ray background in the 8-24 keV band, directly identifying AGNs with obscuring columns up to . In the softer 3-8 keV band the number counts are in general agreement with those measured by XMM-Newton and Chandra over the flux range S(3-8 keV)/ probed by NuSTAR. In the hard 8-24 keV band NuSTAR probes fluxes over the range S(8-24 keV)/, a factor ∼100 fainter than previous measurements. The 8-24 keV number counts match predictions from AGN population synthesis models, directly confirming the existence of a population of obscured and/or hard X-ray sources inferred from the shape of the integrated cosmic X-ray background. The measured NuSTAR counts lie significantly above simple extrapolation with a Euclidian slope to low flux of the Swift/BAT 15-55 keV number counts measured at higher fluxes (S(15-55 keV) 10-11 ), reflecting the evolution of the AGN population between the Swift/BAT local () sample and NuSTAR's sample. CXB synthesis models, which account for AGN evolution, lie above the Swift/BAT measurements, suggesting that they do not fully capture the evolution of obscured AGNs at low redshifts.",

author = "Harrison, {F. A.} and J. Aird and F. Civano and G. Lansbury and Mullaney, {J. R.} and Ballantyne, {D. R.} and Alexander, {D. M.} and D. Stern and M. Ajello and D. Barret and Bauer, {F. E.} and M. Balokovi{\'c} and Brandt, {W. N.} and M. Brightman and Boggs, {S. E.} and Christensen, {F. E.} and A. Comastri and Craig, {W. W.} and {Del Moro}, A. and K. Forster and P. Gandhi and P. Giommi and Grefenstette, {B. W.} and Hailey, {C. J.} and Hickox, {R. C.} and A. Hornstrup and T. Kitaguchi and J. Koglin and B. Luo and Madsen, {K. K.} and Mao, {P. H.} and H. Miyasaka and K. Mori and M. Perri and M. Pivovaroff and S. Puccetti and V. Rana and E. Treister and D. Walton and Westergaard, {N. J.} and D. Wik and L. Zappacosta and Zhang, {W. W.} and A. Zoglauer",

year = "2016",

month = nov,

day = "10",

doi = "10.3847/0004-637X/831/2/185",

language = "English (US)",

volume = "831",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "2",

}

Harrison, FA, Aird, J, Civano, F, Lansbury, G, Mullaney, JR, Ballantyne, DR, Alexander, DM, Stern, D, Ajello, M, Barret, D, Bauer, FE, Baloković, M, Brandt, WN, Brightman, M, Boggs, SE, Christensen, FE, Comastri, A, Craig, WW, Del Moro, A, Forster, K, Gandhi, P, Giommi, P, Grefenstette, BW, Hailey, CJ, Hickox, RC, Hornstrup, A, Kitaguchi, T, Koglin, J, Luo, B, Madsen, KK, Mao, PH, Miyasaka, H, Mori, K, Perri, M, Pivovaroff, M, Puccetti, S, Rana, V, Treister, E, Walton, D, Westergaard, NJ, Wik, D, Zappacosta, L, Zhang, WW & Zoglauer, A 2016, 'THE NuSTAR EXTRAGALACTIC SURVEYS: The NUMBER COUNTS of ACTIVE GALACTIC NUCLEI and the RESOLVED FRACTION of the COSMIC X-RAY BACKGROUND', Astrophysical Journal, vol. 831, no. 2, 185. https://doi.org/10.3847/0004-637X/831/2/185

TY - JOUR

T1 - THE NuSTAR EXTRAGALACTIC SURVEYS

T2 - The NUMBER COUNTS of ACTIVE GALACTIC NUCLEI and the RESOLVED FRACTION of the COSMIC X-RAY BACKGROUND

AU - Harrison, F. A.

AU - Aird, J.

AU - Civano, F.

AU - Lansbury, G.

AU - Mullaney, J. R.

AU - Ballantyne, D. R.

AU - Alexander, D. M.

AU - Stern, D.

AU - Ajello, M.

AU - Barret, D.

AU - Bauer, F. E.

AU - Baloković, M.

AU - Brandt, W. N.

AU - Brightman, M.

AU - Boggs, S. E.

AU - Christensen, F. E.

AU - Comastri, A.

AU - Craig, W. W.

AU - Del Moro, A.

AU - Forster, K.

AU - Gandhi, P.

AU - Giommi, P.

AU - Grefenstette, B. W.

AU - Hailey, C. J.

AU - Hickox, R. C.

AU - Hornstrup, A.

AU - Kitaguchi, T.

AU - Koglin, J.

AU - Luo, B.

AU - Madsen, K. K.

AU - Mao, P. H.

AU - Miyasaka, H.

AU - Mori, K.

AU - Perri, M.

AU - Pivovaroff, M.

AU - Puccetti, S.

AU - Rana, V.

AU - Treister, E.

AU - Walton, D.

AU - Westergaard, N. J.

AU - Wik, D.

AU - Zappacosta, L.

AU - Zhang, W. W.

AU - Zoglauer, A.

PY - 2016/11/10

Y1 - 2016/11/10

N2 - We present the 3-8 keV and 8-24 keV number counts of active galactic nuclei (AGNs) identified in the Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic surveys. NuSTAR has now resolved 33%-39% of the X-ray background in the 8-24 keV band, directly identifying AGNs with obscuring columns up to . In the softer 3-8 keV band the number counts are in general agreement with those measured by XMM-Newton and Chandra over the flux range S(3-8 keV)/ probed by NuSTAR. In the hard 8-24 keV band NuSTAR probes fluxes over the range S(8-24 keV)/, a factor ∼100 fainter than previous measurements. The 8-24 keV number counts match predictions from AGN population synthesis models, directly confirming the existence of a population of obscured and/or hard X-ray sources inferred from the shape of the integrated cosmic X-ray background. The measured NuSTAR counts lie significantly above simple extrapolation with a Euclidian slope to low flux of the Swift/BAT 15-55 keV number counts measured at higher fluxes (S(15-55 keV) 10-11 ), reflecting the evolution of the AGN population between the Swift/BAT local () sample and NuSTAR's sample. CXB synthesis models, which account for AGN evolution, lie above the Swift/BAT measurements, suggesting that they do not fully capture the evolution of obscured AGNs at low redshifts.

AB - We present the 3-8 keV and 8-24 keV number counts of active galactic nuclei (AGNs) identified in the Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic surveys. NuSTAR has now resolved 33%-39% of the X-ray background in the 8-24 keV band, directly identifying AGNs with obscuring columns up to . In the softer 3-8 keV band the number counts are in general agreement with those measured by XMM-Newton and Chandra over the flux range S(3-8 keV)/ probed by NuSTAR. In the hard 8-24 keV band NuSTAR probes fluxes over the range S(8-24 keV)/, a factor ∼100 fainter than previous measurements. The 8-24 keV number counts match predictions from AGN population synthesis models, directly confirming the existence of a population of obscured and/or hard X-ray sources inferred from the shape of the integrated cosmic X-ray background. The measured NuSTAR counts lie significantly above simple extrapolation with a Euclidian slope to low flux of the Swift/BAT 15-55 keV number counts measured at higher fluxes (S(15-55 keV) 10-11 ), reflecting the evolution of the AGN population between the Swift/BAT local () sample and NuSTAR's sample. CXB synthesis models, which account for AGN evolution, lie above the Swift/BAT measurements, suggesting that they do not fully capture the evolution of obscured AGNs at low redshifts.

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UR - http://www.scopus.com/inward/citedby.url?scp=84994496756&partnerID=8YFLogxK

U2 - 10.3847/0004-637X/831/2/185

DO - 10.3847/0004-637X/831/2/185

M3 - Article

AN - SCOPUS:84994496756

SN - 0004-637X

VL - 831

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 185

ER -

THE NuSTAR EXTRAGALACTIC SURVEYS: The NUMBER COUNTS of ACTIVE GALACTIC NUCLEI and the RESOLVED FRACTION of the COSMIC X-RAY BACKGROUND

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