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Title: The 2-79 keV X-ray spectrum of the Circinus galaxy with NuSTAR, XMM-Newton, and Chandra: a fully Compton-thick active galactic nucleus

Abstract

The Circinus galaxy is one of the closest obscured active galactic nuclei (AGNs), making it an ideal target for detailed study. Combining archival Chandra and XMM-Newton data with new NuSTAR observations, we model the 2-79 keV spectrum to constrain the primary AGN continuum and to derive physical parameters for the obscuring material. Chandra's high angular resolution allows a separation of nuclear and off-nuclear galactic emission. In the off-nuclear diffuse emission, we find signatures of strong cold reflection, including high equivalent-width neutral Fe lines. This Compton-scattered off-nuclear emission amounts to 18% of the nuclear flux in the Fe line region, but becomes comparable to the nuclear emission above 30 keV. The new analysis no longer supports a prominent transmitted AGN component in the observed band. We find that the nuclear spectrum is consistent with Compton scattering by an optically thick torus, where the intrinsic spectrum is a power law of photon index Γ = 2.2-2.4, the torus has an equatorial column density of N {sub H} = (6-10) × 10{sup 24} cm{sup –2}, and the intrinsic AGN 2-10 keV luminosity is (2.3-5.1) × 10{sup 42} erg s{sup –1}. These values place Circinus along the same relations as unobscured AGNs in accretionmore » rate versus Γ and L{sub X} versus L {sub IR} phase space. NuSTAR's high sensitivity and low background allow us to study the short timescale variability of Circinus at X-ray energies above 10 keV for the first time. The lack of detected variability favors a Compton-thick absorber, in line with the spectral fitting results.« less

Authors:
;  [1];  [2]; ; ; ; ;  [3];  [4]; ;  [5]; ;  [6];  [7];  [8];  [9];  [10];  [11];  [12];  [13] more »; « less
  1. Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, 306, Santiago 22 (Chile)
  2. ASDC-ASI, Via del Politecnico, I-00133 Roma (Italy)
  3. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
  4. Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland)
  5. Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
  6. Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)
  7. Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748, Garching bei München (Germany)
  8. Danish Technical University, Lyngby (Denmark)
  9. INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
  10. Department of Physics, Durham University, South Road, Durham, DH1 3LE (United Kingdom)
  11. Columbia Astrophysics Laboratory and Department of Physics, Columbia University, 550 West 120th Street, New York, NY 10027 (United States)
  12. Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road M/S 29, Menlo Park, CA 94025 (United States)
  13. Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy)
Publication Date:
OSTI Identifier:
22365334
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 791; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; COMPTON EFFECT; DENSITY; EMISSION; GALAXY NUCLEI; KEV RANGE; LUMINOSITY; PHASE SPACE; PHOTONS; REFLECTION; RESOLUTION; SENSITIVITY; X RADIATION; X-RAY GALAXIES; X-RAY SPECTRA

Citation Formats

Arévalo, P., Bauer, F. E., Puccetti, S., Walton, D. J., Fuerst, F., Grefenstette, B. W., Harrison, F. A., Madsen, K. K., Koss, M., Boggs, S. E., Craig, W. W., Brandt, W. N., Luo, B., Brightman, M., Christensen, F. E., Comastri, A., Gandhi, P., Hailey, C. J., Madejski, G., Marinucci, A., and others, and. The 2-79 keV X-ray spectrum of the Circinus galaxy with NuSTAR, XMM-Newton, and Chandra: a fully Compton-thick active galactic nucleus. United States: N. p., 2014. Web. doi:10.1088/0004-637X/791/2/81.
Arévalo, P., Bauer, F. E., Puccetti, S., Walton, D. J., Fuerst, F., Grefenstette, B. W., Harrison, F. A., Madsen, K. K., Koss, M., Boggs, S. E., Craig, W. W., Brandt, W. N., Luo, B., Brightman, M., Christensen, F. E., Comastri, A., Gandhi, P., Hailey, C. J., Madejski, G., Marinucci, A., & others, and. The 2-79 keV X-ray spectrum of the Circinus galaxy with NuSTAR, XMM-Newton, and Chandra: a fully Compton-thick active galactic nucleus. United States. https://doi.org/10.1088/0004-637X/791/2/81
Arévalo, P., Bauer, F. E., Puccetti, S., Walton, D. J., Fuerst, F., Grefenstette, B. W., Harrison, F. A., Madsen, K. K., Koss, M., Boggs, S. E., Craig, W. W., Brandt, W. N., Luo, B., Brightman, M., Christensen, F. E., Comastri, A., Gandhi, P., Hailey, C. J., Madejski, G., Marinucci, A., and others, and. 2014. "The 2-79 keV X-ray spectrum of the Circinus galaxy with NuSTAR, XMM-Newton, and Chandra: a fully Compton-thick active galactic nucleus". United States. https://doi.org/10.1088/0004-637X/791/2/81.
@article{osti_22365334,
title = {The 2-79 keV X-ray spectrum of the Circinus galaxy with NuSTAR, XMM-Newton, and Chandra: a fully Compton-thick active galactic nucleus},
author = {Arévalo, P. and Bauer, F. E. and Puccetti, S. and Walton, D. J. and Fuerst, F. and Grefenstette, B. W. and Harrison, F. A. and Madsen, K. K. and Koss, M. and Boggs, S. E. and Craig, W. W. and Brandt, W. N. and Luo, B. and Brightman, M. and Christensen, F. E. and Comastri, A. and Gandhi, P. and Hailey, C. J. and Madejski, G. and Marinucci, A. and others, and},
abstractNote = {The Circinus galaxy is one of the closest obscured active galactic nuclei (AGNs), making it an ideal target for detailed study. Combining archival Chandra and XMM-Newton data with new NuSTAR observations, we model the 2-79 keV spectrum to constrain the primary AGN continuum and to derive physical parameters for the obscuring material. Chandra's high angular resolution allows a separation of nuclear and off-nuclear galactic emission. In the off-nuclear diffuse emission, we find signatures of strong cold reflection, including high equivalent-width neutral Fe lines. This Compton-scattered off-nuclear emission amounts to 18% of the nuclear flux in the Fe line region, but becomes comparable to the nuclear emission above 30 keV. The new analysis no longer supports a prominent transmitted AGN component in the observed band. We find that the nuclear spectrum is consistent with Compton scattering by an optically thick torus, where the intrinsic spectrum is a power law of photon index Γ = 2.2-2.4, the torus has an equatorial column density of N {sub H} = (6-10) × 10{sup 24} cm{sup –2}, and the intrinsic AGN 2-10 keV luminosity is (2.3-5.1) × 10{sup 42} erg s{sup –1}. These values place Circinus along the same relations as unobscured AGNs in accretion rate versus Γ and L{sub X} versus L {sub IR} phase space. NuSTAR's high sensitivity and low background allow us to study the short timescale variability of Circinus at X-ray energies above 10 keV for the first time. The lack of detected variability favors a Compton-thick absorber, in line with the spectral fitting results.},
doi = {10.1088/0004-637X/791/2/81},
url = {https://www.osti.gov/biblio/22365334}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 791,
place = {United States},
year = {Wed Aug 20 00:00:00 EDT 2014},
month = {Wed Aug 20 00:00:00 EDT 2014}
}

Works referencing / citing this record:

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An Iwasawa–Taniguchi effect for Compton-thick active galactic nuclei
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Compton Shoulder Diagnostics in Active Galactic Nuclei for Probing the Metallicity of the Obscuring Compton-thick Tori
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Circumnuclear Multiphase Gas in the Circinus Galaxy. II. The Molecular and Atomic Obscuring Structures Revealed with ALMA
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Deep Chandra Observations of ESO 428-G014. IV. The Morphology of the Nuclear Region in the Hard Continuum and Fe K α Line
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XCLUMPY: X-Ray Spectral Model from Clumpy Torus and Its Application to the Circinus Galaxy
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Measuring the Obscuring Column of a Disk Megamaser AGN in a Nearby Merger
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NuSTAR Uncovers an Extremely Local Compton-thick AGN in NGC 4968
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BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift /BAT 70-month AGN Catalog
journal, December 2017