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Published September 1, 2025 | Version Published
Journal Article Open

BASS. XLIX. Characterization of Highly Luminous and Obscured AGNs: Local X-Ray and [Ne V] λ<3426 Emission in Comparison with the High-redshift Universe

Creators

  • 1. ROR icon Eureka Scientific
  • 2. ROR icon Yale University
  • 3. ROR icon Space Science Institute
  • 4. ROR icon Korea Astronomy and Space Science Institute
  • 5. ROR icon Diego Portales University
  • 6. ROR icon Peking University
  • 7. ROR icon Tel Aviv University
  • 8. ROR icon Max Planck Institute for Extraterrestrial Physics
  • 9. ROR icon Excellence Cluster Origins
  • 10. ROR icon University of Maryland, College Park
  • 11. ROR icon University of Tarapacá
  • 12. ROR icon European Southern Observatory
  • 13. ROR icon Tohoku University
  • 14. INAF–Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone (RM), Italy
  • 15. ROR icon Pontificia Universidad Católica de Chile
  • 16. ROR icon University of Bologna
  • 17. ROR icon Roma Tre University
  • 18. ROR icon Arcetri Astrophysical Observatory
  • 19. ROR icon European Space Research and Technology Centre
  • 20. ROR icon University of Hertfordshire
  • 21. ROR icon Atacama Large Millimeter Submillimeter Array
  • 22. INAF—Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, I-40129 Bologna, Italy
  • 23. ROR icon Texas A&M University
  • 24. ROR icon Leiden University
  • 25. ROR icon Australia Telescope National Facility
  • 26. ROR icon California Institute of Technology
  • 27. ROR icon Wayne State University
  • 28. ROR icon Jet Propulsion Lab
  • 29. ROR icon University of Hawaii at Manoa

Abstract

We present a detailed analysis of the most luminous and obscured active galactic nuclei (AGNs) detected in the ultra-hard X-ray band (14–195 kev) by the Swift/Burst Alert Telescope. Our sample comprises 21 X-ray luminous (log L_X / erg s⁻¹ > 44.6, 2–10 keV) AGNs at z < 0.6, optically classified as Seyfert 1.9 and 2. Using NuSTAR, XMM-Newton, Suzaku, and Chandra data, we constrain AGN properties such as absorption column density N_H, photon index Γ, intrinsic L_X, covering factor, and iron Kα equivalent width. We find median line-of-sight log N_H / cm⁻² = 23.5_(−1.2)^(+0.5) and 2–10 keV rest-frame, de-absorbed log L_X / erg s⁻¹ = 44.7_(−0.6)^(+0.8), at the 5th and 95th percentiles. For sources with black hole mass estimates (12/20), we find a weak correlation between Γ and Eddington ratio (λ_(Edd)). Of these, six (50% ± 13%) lie in the N_H-λ_(Edd) "forbidden region" and exhibit a combined higher prevalence of N_H variability and outflow signatures, suggesting a transitional phase where AGN feedback may be clearing the obscuring material. For the 13/21 sources with multi-epoch X-ray spectroscopy, 85_(-15)_(+5)% exhibit variability in either 2–10 keV flux (77_(−15)^(+8)%) or line-of-sight N_H (33_(−10^(+15)%). For the 20/21 sources with available near-UV/optical spectroscopy, we detect [Ne v]λ3426 in 17 (85_(−11)^(+5)%), confirming its reliability to probe AGN emission even in heavily obscured systems. When renormalized to the same [O iii]λ5007 peak flux as z = 2−9 narrow-line AGNs identified with JWST, our sample exhibits significantly stronger [Ne v]λ3426 emission, suggesting that high-redshift obscured AGNs may be intrinsically weaker in [Ne v]λ3426 or that [Ne v]λ3426 is more challenging to detect in those environments. The sources presented in this work serve as a benchmark for high-redshift analogs, showing the potential of [Ne v]λ3426 to reveal obscured AGNs and the need for future missions to expand X-ray studies into the high-redshift Universe.

Copyright and License

© 2025. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

We acknowledge the anonymous referee for the valuable comments that improved the quality of the paper. A.P. acknowledges D. Costanzo for all the support over the years. A.P. and M.K. acknowledge support from NASA through ADAP award 80NSSC22K1126 and NuSTAR grants 80NSSC22K1933 and 80NSSC22K1934. K.O. acknowledges support from the Korea Astronomy and Space Science Institute under the R&D program (Project No. 2025-1-831-01), supervised by the Korea AeroSpace Administration, and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2025-00553982). B.T. acknowledges support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 950533) and from the Israel Science Foundation (grant No. 1849/19). C.R. acknowledges support from Fondecyt Regular grant 1230345, ANID BASAL project FB210003, and the China-Chile joint research fund. A.T. acknowledges financial support from the Bando Ricerca Fondamentale INAF 2022 Large Grant “Toward a holistic view of the Titans: multiband observations of z > 6 QSOs powered by greedy SMBHs.” I.M.C. acknowledges support from ANID program FONDECYT Postdoctorado 3230653. M.S. acknowledges financial support from the Italian Ministry for University and Research, through the grant PNRR-M4C2-I1.1-PRIN 2022-PE9-SEAWIND: Super-Eddington Accretion: Wind, INflow and Disk—F53D23001250006-NextGenerationEU.

Facilities

NuSTAR, XMM, Chandra, Suzaku. -

Software References

NuSTARDAS v2.1.2,45 SAS v21.0.0 (C. Gabriel et al. 2004), CIAO v4.16.0 (A. Fruscione et al. 2006), PyXspec v2.1.3 (K. A. Arnaud 1996; C. Gordon & K. Arnaud 2021), TOPCAT v4.94.9 (M. B. Taylor 2005), Astropy v5.0 (Astropy Collaboration et al. 2013, 2018, 2022); Pandas v1.4.1 (The pandas development team 2020), SciPy v1.13.1 (P. Virtanen et al. 2020), Matplotlib v3.4.3 (J. D. Hunter 2007), linmix v0.1.0 (B. C. Kelly 2007).

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Additional details

Related works

Is new version of
Discussion Paper: arXiv:2507.10674 (arXiv)
Is supplemented by
Dataset: 10.25574/cdc.408 (DOI)

Funding

National Aeronautics and Space Administration
80NSSC22K1126
National Aeronautics and Space Administration
80NSSC22K1933
National Aeronautics and Space Administration
80NSSC22K1934
Korea Astronomy and Space Science Institute
2025-1-831-01
National Research Foundation of Korea
RS-2025-00553982
European Research Council
950533
Israel Science Foundation
1849/19
Fondo Nacional de Desarrollo Científico y Tecnológico
1230345
Agencia Nacional de Investigación y Desarrollo
FB210003
Chinese Academy of Science South America Center for Astronomy
National Institute for Astrophysics
INAF 2022
Fondo Nacional de Desarrollo Científico y Tecnológico
3230653
Ministero dell'università e della ricerca
PNRR-M4C2-I1.1-PRIN 2022-PE9-SEAWIND
European Union
NextGenerationEU F53D23001250006

Dates

Submitted
2025-04-17
Accepted
2025-07-02
Available
2025-08-21
Published

Caltech Custom Metadata

Caltech groups
Astronomy Department, NuSTAR, Division of Physics, Mathematics and Astronomy (PMA)
Publication Status
Published