A New Compton-thick AGN in Our Cosmic Backyard: Unveiling the Buried Nucleus in NGC 1448 with NuSTAR

Publication: Research - peer-reviewJournal article – Annual report year: 2017

DOI

  • Author: Annuar, A.

    University of Durham, United Kingdom

  • Author: Alexander, D. M.

    University of Durham, United Kingdom

  • Author: Gandhi, P.

    University of Southampton, United Kingdom

  • Author: Lansbury, G. B.

    University of Durham, United Kingdom

  • Author: Asmus, K.-D.

    European Southern Observatory, Chile

  • Author: Ballantyne, D. R.

    Georgia Institute of Technology, United States

  • Author: Bauer, F. E.

    Pontificia Universidad Catolica de Chile, Chile

  • Author: Boggs, S. E.

    University of California at Berkeley, United Kingdom

  • Author: Boorman, P. G.

    University of Southampton, United Kingdom

  • Author: Brandt, W. N.

    Pennsylvania State University, United States

  • Author: Brightman, M.

    California Institute of Technology, United States

  • Author: Christensen, Finn Erland

    Astrophysics and Atmospheric Physics, National Space Institute, Technical University of Denmark, Elektrovej, 2800, Kgs. Lyngby, Denmark

  • Author: Craig, W. W.

    University of California at Berkeley, United States

  • Author: Farrah, D.

    Virginia Polytechnic Institute and State University, United States

  • Author: Goulding, A. D.

    Princeton University, United States

  • Author: Hailey, C. J.

    Columbia University, United States

  • Author: Harrison, F. A.

    Cahill Center for Astronomy and Astrophysics, United States

  • Author: Koss, Michael J.

    ETH Zurich, Switzerland

  • Author: LaMassa, S. M.

    NASA Goddard Space Flight Center, United States

  • Author: Murray, S. S.

    Harvard University, United States

  • Author: Ricci, C.

    Pontificia Universidad Catolica de Chile, Chile

  • Author: Rosario, D. J.

    University of Durham, United Kingdom

  • Author: Stanley, F.

    University of Durham, United Arab Emirates

  • Author: Stern, D.

    California Institute of Technology, United Kingdom

  • Author: Zhang, W.

    NASA Goddard Space Flight Center, United States

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NGC 1448 is one of the nearest luminous galaxies (L 8-1000μm >109 L o) to ours (z = 0.00390), and yet the active galactic nucleus (AGN) it hosts was only recently discovered, in 2009. In this paper, we present an analysis of the nuclear source across three wavebands: mid-infrared (MIR) continuum, optical, and X-rays. We observed the source with the Nuclear Spectroscopic Telescope Array (NuSTAR), and combined these data with archival Chandra data to perform broadband X-ray spectral fitting (≈0.5-40 keV) of the AGN for the first time. Our X-ray spectral analysis reveals that the AGN is buried under a Compton-thick (CT) column of obscuring gas along our line of sight, with a column density of N H(los) ≥2.5 ×1024 cm-2. The best-fitting torus models measured an intrinsic 2-10 keV luminosity of L (3.5-7.6) ×1040 erg s-1, making NGC 1448 one of the lowest luminosity CTAGNs known. In addition to the NuSTAR observation, we also performed optical spectroscopy for the nucleus in this edge-on galaxy using the European Southern Observatory New Technology Telescope. We re-classify the optical nuclear spectrum as a Seyfert on the basis of the Baldwin-Philips-Terlevich diagnostic diagrams, thus identifying the AGN at optical wavelengths for the first time. We also present high spatial resolution MIR observations of NGC 1448 with Gemini/T-ReCS, in which a compact nucleus is clearly detected. The absorption-corrected 2-10 keV luminosity measured from our X-ray spectral analysis agrees with that predicted from the optical [O iii]λ5007 Å emission line and the MIR 12 μm continuum, further supporting the CT nature of the AGN.

Original languageEnglish
Article number165
JournalAstrophysical Journal
Volume836
Issue number2
Number of pages13
ISSN0004-637X
DOIs
StatePublished - 2017
CitationsWeb of Science® Times Cited: 2

    Keywords

  • Galaxies: active, Galaxies: nuclei, Techniques: spectroscopic, X-rays: galaxies, X-rays: individual (NGC 1448)
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