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A New Compton-Thick AGN in Our Cosmic Backyard: Unveiling the Buried Nucleus in NGC 1448 with NuSTARNGC 1448 is one of the nearest luminous galaxies [L(sub 8) - 1000 micrometers is greater than 10(exp. 9) Solar Luminosity] 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 ( approx. equals 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(sub H)(los) approx. greater than 2.5 x 10(exp. 24) cm(exp. -2). The best-fitting torus models measured an intrinsic 2-10 keV luminosity of L(sub 2)-10,int = (3.5 - 7.6) x 10(exp. 40) erg s(exp. -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 reclassify 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] Lamda 5007 A emission line and the MIR 12 micrometer continuum, further supporting the CT nature ofthe AGN.
Document ID
20170006067
Document Type
Reprint (Version printed in journal)
Authors
Annuar, A. (Durham Univ. United Kingdom)
Alexander, D. M. (Durham Univ. United Kingdom)
Ghandi, P. (Southampton Univ. United Kingdom)
Lansbury, G. B. (Durham Univ. United Kingdom)
Asmus, D. (European Southern Observatory Santiago, Chile)
Ballantyne, D. R. (Georgia Inst. of Tech. Atlanta, GA, United States)
Bauer, F. E. (Pontificia Univ. Catolica de Chile Santiago, Chile)
Boggs, S. E. (California Univ. Berkeley, CA, United States)
Boorman, P. G. (Southampton Univ. United Kingdom)
Brandt, W. N. (Pennsylvania State Univ. University Park, PA, United States)
Brightman, M. (California Inst. of Tech. Pasadena, CA, United States)
Christensen, F. E. (Technical Univ. of Denmark Lyngby, Denmark)
Craig, W. W. (California Univ. Berkeley, CA, United States)
Farrah, D. (Virginia Tech Blacksburg, VA, United States)
Goulding, A. D. (Princeton Univ. Princeton, NJ, United States)
Hailey, C. J. (Columbia Univ. New York, NY, United States)
Harrison, F. A. (California Inst. of Tech. Pasadena, CA, United States)
Koss, M. J. (Eidgenoessische Technische Hochschule Zurich, Switzerland)
LaMassa, S. M. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Murray, S. S. (Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Ricci, C. (Pontificia Univ. Catolica de Chile Santiago, Chile)
Rosario, D. J. (Durham Univ. United Kingdom)
Stanley, F. (Durham Univ. United Kingdom)
Stern, D. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Zhang, William W. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
July 3, 2017
Publication Date
February 17, 2017
Publication Information
Publication: The Astrophysical Journal
Volume: 836
Issue: 2
ISSN: 0004-637X
Subject Category
Statistics and Probability
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN44063
Distribution Limits
Public
Copyright
Other
Keywords
galaxies: active – galaxies: nuclei – techniques: spectroscopic – X-rays: