The NuSTAR Extragalactic Survey: First Direct Measurements of the Greater Than Or Similar To 10 Kev X-Ray Luminosity Function For Active Galactic Nuclei At z > 0.1

J. Aird, D. M. Alexander, D. R. Ballantyne, F. Civano, A. Del-Moro, R. C. Hickox, G. B. Lansbury, J. R. Mullaney, F. E. Bauer, W. N. Brandt, A. Comastri, A. C. Fabian, P. Gandhi, F. A. Harrison, Birong Luo, D. Stern, E. Treister, L. Zappacosta, M. Ajello, R. Assef & 17 others M. Balokovic, S. E. Boggs, M. Brightman, Finn Erland Christensen, W. W. Craig, M. Elvis, K. Forster, B. W. Grefenstette, C. J. Hailey, M. Koss, S. M. LaMassa, K. K. Madsen, S. Puccetti, C. Saez, C. M. Urry, D. R. Wik, W. Zhang

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Abstract

We present the first direct measurements of the rest-frame 10-40 keV X-ray luminosity function (XLF) of active galactic nuclei (AGNs) based on a sample of 94 sources at 0.1 <z <3, selected at 8-24 keV energies from sources in the Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic survey program. Our results are consistent with the strong evolution of the AGN population seen in prior, lower-energy studies of the XLF. However, different models of the intrinsic distribution of absorption, which are used to correct for selection biases, give significantly different predictions for the total number of sources in our sample, leading to small, systematic differences in our binned estimates of the XLF. Adopting a model with a lower intrinsic fraction of Compton-thick sources and a larger population of sources with column densities NH ∼1023-24 cm-2 or a model with stronger Compton reflection component (with a relative normalization of R ∼ 2 at all luminosities) can bring extrapolations of the XLF from 2-10 keV into agreement with our NuSTAR sample. Ultimately, X-ray spectral analysis of the NuSTAR sources is required to break this degeneracy between the distribution of absorbing column densities and the strength of the Compton reflection component and thus refine our measurements of the XLF. Furthermore, the models that successfully describe the high-redshift population seen by NuSTAR tend to over-predict previous, high-energy measurements of the local XLF, indicating that there is evolution of the AGN population that is not fully captured by the current models.
Original languageEnglish
Article number66
JournalAstrophysical Journal
Volume815
Issue number1
Number of pages13
ISSN0004-637X
DOIs
Publication statusPublished - 2015

Keywords

  • Galaxies: active
  • Galaxies: evolution
  • X-rays: galaxies

Cite this

Aird, J. ; Alexander, D. M. ; Ballantyne, D. R. ; Civano, F. ; Del-Moro, A. ; Hickox, R. C. ; Lansbury, G. B. ; Mullaney, J. R. ; Bauer, F. E. ; Brandt, W. N. ; Comastri, A. ; Fabian, A. C. ; Gandhi, P. ; Harrison, F. A. ; Luo, Birong ; Stern, D. ; Treister, E. ; Zappacosta, L. ; Ajello, M. ; Assef, R. ; Balokovic, M. ; Boggs, S. E. ; Brightman, M. ; Christensen, Finn Erland ; Craig, W. W. ; Elvis, M. ; Forster, K. ; Grefenstette, B. W. ; Hailey, C. J. ; Koss, M. ; LaMassa, S. M. ; Madsen, K. K. ; Puccetti, S. ; Saez, C. ; Urry, C. M. ; Wik, D. R. ; Zhang, W. / The NuSTAR Extragalactic Survey: First Direct Measurements of the Greater Than Or Similar To 10 Kev X-Ray Luminosity Function For Active Galactic Nuclei At z > 0.1. In: Astrophysical Journal. 2015 ; Vol. 815, No. 1.
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title = "The NuSTAR Extragalactic Survey: First Direct Measurements of the Greater Than Or Similar To 10 Kev X-Ray Luminosity Function For Active Galactic Nuclei At z > 0.1",
abstract = "We present the first direct measurements of the rest-frame 10-40 keV X-ray luminosity function (XLF) of active galactic nuclei (AGNs) based on a sample of 94 sources at 0.1 Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic survey program. Our results are consistent with the strong evolution of the AGN population seen in prior, lower-energy studies of the XLF. However, different models of the intrinsic distribution of absorption, which are used to correct for selection biases, give significantly different predictions for the total number of sources in our sample, leading to small, systematic differences in our binned estimates of the XLF. Adopting a model with a lower intrinsic fraction of Compton-thick sources and a larger population of sources with column densities NH ∼1023-24 cm-2 or a model with stronger Compton reflection component (with a relative normalization of R ∼ 2 at all luminosities) can bring extrapolations of the XLF from 2-10 keV into agreement with our NuSTAR sample. Ultimately, X-ray spectral analysis of the NuSTAR sources is required to break this degeneracy between the distribution of absorbing column densities and the strength of the Compton reflection component and thus refine our measurements of the XLF. Furthermore, the models that successfully describe the high-redshift population seen by NuSTAR tend to over-predict previous, high-energy measurements of the local XLF, indicating that there is evolution of the AGN population that is not fully captured by the current models.",
keywords = "Galaxies: active, Galaxies: evolution, X-rays: galaxies",
author = "J. Aird and Alexander, {D. M.} and Ballantyne, {D. R.} and F. Civano and A. Del-Moro and Hickox, {R. C.} and Lansbury, {G. B.} and Mullaney, {J. R.} and Bauer, {F. E.} and Brandt, {W. N.} and A. Comastri and Fabian, {A. C.} and P. Gandhi and Harrison, {F. A.} and Birong Luo and D. Stern and E. Treister and L. Zappacosta and M. Ajello and R. Assef and M. Balokovic and Boggs, {S. E.} and M. Brightman and Christensen, {Finn Erland} and Craig, {W. W.} and M. Elvis and K. Forster and Grefenstette, {B. W.} and Hailey, {C. J.} and M. Koss and LaMassa, {S. M.} and Madsen, {K. K.} and S. Puccetti and C. Saez and Urry, {C. M.} and Wik, {D. R.} and W. Zhang",
year = "2015",
doi = "10.1088/0004-637x/815/1/66",
language = "English",
volume = "815",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing",
number = "1",

}

Aird, J, Alexander, DM, Ballantyne, DR, Civano, F, Del-Moro, A, Hickox, RC, Lansbury, GB, Mullaney, JR, Bauer, FE, Brandt, WN, Comastri, A, Fabian, AC, Gandhi, P, Harrison, FA, Luo, B, Stern, D, Treister, E, Zappacosta, L, Ajello, M, Assef, R, Balokovic, M, Boggs, SE, Brightman, M, Christensen, FE, Craig, WW, Elvis, M, Forster, K, Grefenstette, BW, Hailey, CJ, Koss, M, LaMassa, SM, Madsen, KK, Puccetti, S, Saez, C, Urry, CM, Wik, DR & Zhang, W 2015, 'The NuSTAR Extragalactic Survey: First Direct Measurements of the Greater Than Or Similar To 10 Kev X-Ray Luminosity Function For Active Galactic Nuclei At z > 0.1', Astrophysical Journal, vol. 815, no. 1, 66. https://doi.org/10.1088/0004-637x/815/1/66

The NuSTAR Extragalactic Survey: First Direct Measurements of the Greater Than Or Similar To 10 Kev X-Ray Luminosity Function For Active Galactic Nuclei At z > 0.1. / Aird, J.; Alexander, D. M.; Ballantyne, D. R.; Civano, F.; Del-Moro, A.; Hickox, R. C.; Lansbury, G. B.; Mullaney, J. R.; Bauer, F. E.; Brandt, W. N.; Comastri, A.; Fabian, A. C.; Gandhi, P.; Harrison, F. A.; Luo, Birong; Stern, D.; Treister, E.; Zappacosta, L.; Ajello, M.; Assef, R.; Balokovic, M.; Boggs, S. E.; Brightman, M.; Christensen, Finn Erland; Craig, W. W.; Elvis, M.; Forster, K.; Grefenstette, B. W.; Hailey, C. J.; Koss, M.; LaMassa, S. M.; Madsen, K. K.; Puccetti, S.; Saez, C.; Urry, C. M.; Wik, D. R.; Zhang, W.

In: Astrophysical Journal, Vol. 815, No. 1, 66, 2015.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - The NuSTAR Extragalactic Survey: First Direct Measurements of the Greater Than Or Similar To 10 Kev X-Ray Luminosity Function For Active Galactic Nuclei At z > 0.1

AU - Aird, J.

AU - Alexander, D. M.

AU - Ballantyne, D. R.

AU - Civano, F.

AU - Del-Moro, A.

AU - Hickox, R. C.

AU - Lansbury, G. B.

AU - Mullaney, J. R.

AU - Bauer, F. E.

AU - Brandt, W. N.

AU - Comastri, A.

AU - Fabian, A. C.

AU - Gandhi, P.

AU - Harrison, F. A.

AU - Luo, Birong

AU - Stern, D.

AU - Treister, E.

AU - Zappacosta, L.

AU - Ajello, M.

AU - Assef, R.

AU - Balokovic, M.

AU - Boggs, S. E.

AU - Brightman, M.

AU - Christensen, Finn Erland

AU - Craig, W. W.

AU - Elvis, M.

AU - Forster, K.

AU - Grefenstette, B. W.

AU - Hailey, C. J.

AU - Koss, M.

AU - LaMassa, S. M.

AU - Madsen, K. K.

AU - Puccetti, S.

AU - Saez, C.

AU - Urry, C. M.

AU - Wik, D. R.

AU - Zhang, W.

PY - 2015

Y1 - 2015

N2 - We present the first direct measurements of the rest-frame 10-40 keV X-ray luminosity function (XLF) of active galactic nuclei (AGNs) based on a sample of 94 sources at 0.1 Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic survey program. Our results are consistent with the strong evolution of the AGN population seen in prior, lower-energy studies of the XLF. However, different models of the intrinsic distribution of absorption, which are used to correct for selection biases, give significantly different predictions for the total number of sources in our sample, leading to small, systematic differences in our binned estimates of the XLF. Adopting a model with a lower intrinsic fraction of Compton-thick sources and a larger population of sources with column densities NH ∼1023-24 cm-2 or a model with stronger Compton reflection component (with a relative normalization of R ∼ 2 at all luminosities) can bring extrapolations of the XLF from 2-10 keV into agreement with our NuSTAR sample. Ultimately, X-ray spectral analysis of the NuSTAR sources is required to break this degeneracy between the distribution of absorbing column densities and the strength of the Compton reflection component and thus refine our measurements of the XLF. Furthermore, the models that successfully describe the high-redshift population seen by NuSTAR tend to over-predict previous, high-energy measurements of the local XLF, indicating that there is evolution of the AGN population that is not fully captured by the current models.

AB - We present the first direct measurements of the rest-frame 10-40 keV X-ray luminosity function (XLF) of active galactic nuclei (AGNs) based on a sample of 94 sources at 0.1 Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic survey program. Our results are consistent with the strong evolution of the AGN population seen in prior, lower-energy studies of the XLF. However, different models of the intrinsic distribution of absorption, which are used to correct for selection biases, give significantly different predictions for the total number of sources in our sample, leading to small, systematic differences in our binned estimates of the XLF. Adopting a model with a lower intrinsic fraction of Compton-thick sources and a larger population of sources with column densities NH ∼1023-24 cm-2 or a model with stronger Compton reflection component (with a relative normalization of R ∼ 2 at all luminosities) can bring extrapolations of the XLF from 2-10 keV into agreement with our NuSTAR sample. Ultimately, X-ray spectral analysis of the NuSTAR sources is required to break this degeneracy between the distribution of absorbing column densities and the strength of the Compton reflection component and thus refine our measurements of the XLF. Furthermore, the models that successfully describe the high-redshift population seen by NuSTAR tend to over-predict previous, high-energy measurements of the local XLF, indicating that there is evolution of the AGN population that is not fully captured by the current models.

KW - Galaxies: active

KW - Galaxies: evolution

KW - X-rays: galaxies

U2 - 10.1088/0004-637x/815/1/66

DO - 10.1088/0004-637x/815/1/66

M3 - Journal article

VL - 815

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 66

ER -