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NuSTAR Survey of Obscured Swift/BAT-selected Active Galactic Nuclei. II. Median High-energy Cutoff in Seyfert II Hard X-Ray Spectra

Baloković, M. and Harrison, F. A. and Madejski, G. and Comastri, A. and Ricci, C. and Annuar, A. and Ballantyne, D. R. and Boorman, P. and Brandt, W. N. and Brightman, M. and Gandhi, P. and Kamraj, N. and Koss, M. J. and Marchesi, S. and Marinucci, A. and Masini, A. and Matt, G. and Stern, D. and Urry, C. M. (2020) NuSTAR Survey of Obscured Swift/BAT-selected Active Galactic Nuclei. II. Median High-energy Cutoff in Seyfert II Hard X-Ray Spectra. Astrophysical Journal, 905 (1). Art. No. 41. ISSN 1538-4357.

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Broadband X-ray spectroscopy of the X-ray emission produced in the coronae of active galactic nuclei (AGNs) can provide important insights into the physical conditions very close to their central supermassive black holes. The temperature of the Comptonizing plasma that forms the corona is manifested through a high-energy cutoff that has been difficult to directly constrain even in the brightest AGN because it requires high-quality data at energies above 10 keV. In this paper we present a large collection of coronal cutoff constraints for obscured AGNs based on a sample of 130 AGNs selected in the hard X-ray band with Swift/BAT and observed nearly simultaneously with NuSTAR and Swift/XRT. We find that under a reasonable set of assumptions regarding partial constraints the median cutoff is well constrained to 290 ± 20 keV, where the uncertainty is statistical and given at the 68% confidence level. We investigate the sensitivity of this result to our assumptions and find that consideration of various known systematic uncertainties robustly places the median cutoff between 240 and 340 keV. The central 68% of the intrinsic cutoff distribution is found to be between about 140 and 500 keV, with estimated uncertainties of 20 and 100 keV, respectively. In comparison with the literature, we find no clear evidence that the cutoffs in obscured and unobscured AGNs are substantially different. Our analysis highlights the importance of carefully considering partial and potentially degenerate constraints on the coronal high-energy cutoff in AGNs.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Baloković, M.0000-0003-0476-6647
Harrison, F. A.0000-0003-2992-8024
Comastri, A.0000-0003-3451-9970
Ricci, C.0000-0001-5231-2645
Annuar, A.0000-0003-0387-1429
Ballantyne, D. R.0000-0001-8128-6976
Boorman, P.0000-0001-9379-4716
Brandt, W. N.0000-0002-0167-2453
Brightman, M.0000-0002-8147-2602
Gandhi, P.0000-0003-3105-2615
Kamraj, N.0000-0002-3233-2451
Koss, M. J.0000-0002-7998-9581
Marchesi, S.0000-0001-5544-0749
Marinucci, A.0000-0002-2055-4946
Masini, A.0000-0002-7100-9366
Matt, G.0000-0002-2152-0916
Stern, D.0000-0003-2686-9241
Urry, C. M.0000-0002-0745-9792
Additional Information:© 2020. The American Astronomical Society. Received 2020 April 19; revised 2020 August 7; accepted 2020 August 25; published 2020 December 11. The authors appreciate helpful suggestions from the anonymous referee, which helped to improve the clarity of the paper. M.B. acknowledges support from the YCAA Prize Postdoctoal Fellowship, the National Aeronautics and Space Administration (NASA) under the NASA Earth and Space Science Fellowship program (grant NNX14AQ07H), and support from the Black Hole Initiative at Harvard University, which is funded in part by the Gordon and Betty Moore Foundation (grant GBMF8273) and in part by the John Templeton Foundation. A.C. and G.M. acknowledge support from the ASI/INAF grant I/037/12/0 and the Caltech Kingsley fellowship program. A.A. acknowledges financial support from Ministry of Education Malaysia Fundamental Research Grant Scheme grant code FRGS/1/2019/STG02/UKM/02/7. P.B. acknowledges financial support from the STFC and the Czech Science Foundation project No. 19-05599Y. P.G. acknowledges support from the STFC and a UGC/UKIERI Thematic Partnership. We have 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 has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the Space Science Data Center (SSDC; ASI, Italy) and the California Institute of Technology (USA). Part of this work is based on archival data, software, or online services provided by the SSDC. This research has made use of the High Energy Astrophysics Science Archive Research Center Online Service, provided by the NASA/Goddard Space Flight Center and NASA's Astrophysics Data System. Facilities: NuSTAR - The NuSTAR (Nuclear Spectroscopic Telescope Array) mission, Swift. - Software: Astropy (Astropy Collaboration et al. 2013, 2018), ASURV (Feigelson et al. 2014), Matplotlib (Hunter 2007), Xspec (Arnaud 1996).
Group:Astronomy Department, Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Yale Center for Astronomy and AstrophysicsUNSPECIFIED
Gordon and Betty Moore FoundationGBMF8273
NASA Earth and Space Science FellowshipNNX14AQ07H
John Templeton FoundationUNSPECIFIED
Agenzia Spaziale Italiana (ASI)I/037/12/0
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Lewis A. Kingsley FellowshipUNSPECIFIED
Ministry of Education (Malaysia)FRGS/1/2019/STG02/UKM/02/7
Science and Technology Facilities Council (STFC)UNSPECIFIED
Czech Science Foundation19-05599Y
UK India Education Research Initiative (UKIERI)UNSPECIFIED
Subject Keywords:Active galactic nuclei ; X-ray active galactic nuclei ; Seyfert galaxies ; High energy astrophysics ; X-ray surveys
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Supernovae (1668); Compact objects (288); White dwarf stars (1799)
Record Number:CaltechAUTHORS:20201215-141036856
Persistent URL:
Official Citation:M. Baloković et al 2020 ApJ 905 41
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107093
Deposited By: George Porter
Deposited On:16 Dec 2020 15:10
Last Modified:16 Dec 2020 15:10

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