A Caltech Library Service

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

Annuar, A. and Alexander, D. M. and Gandhi, P. and Lansbury, G. B. and Asmus, D. and Ballantyne, D. R. and Bauer, F. E. and Boggs, S. E. and Boorman, P. G. and Brandt, W. N. and Brightman, M. and Christensen, F. E. and Craig, W. W. and Farrah, D. and Goulding, A. D. and Hailey, C. J. and Harrison, F. A. and Koss, M. J. and LaMassa, S. M. and Murray, S. S. and Ricci, C. and Rosario, D. J. and Stanley, F. and Stern, D. and Zhang, W. (2017) A New Compton-thick AGN in Our Cosmic Backyard: Unveiling the Buried Nucleus in NGC 1448 with NuSTAR. Astrophysical Journal, 836 (2). Art. No. 165. ISSN 0004-637X.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


NGC 1448 is one of the nearest luminous galaxies (L_(8–1000μm) > 10^9 L⊙) 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 × 10^(24) cm^(−2). The best-fitting torus models measured an intrinsic 2–10 keV luminosity of L_(2-10,int) (3.5–7.6) × 10^(40) 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Annuar, A.0000-0003-0387-1429
Alexander, D. M.0000-0002-5896-6313
Gandhi, P.0000-0003-3105-2615
Lansbury, G. B.0000-0002-5328-9827
Asmus, D.0000-0003-0220-2063
Ballantyne, D. R.0000-0001-8128-6976
Bauer, F. E.0000-0002-8686-8737
Boggs, S. E.0000-0001-9567-4224
Boorman, P. G.0000-0001-9379-4716
Brandt, W. N.0000-0002-0167-2453
Brightman, M.0000-0002-8147-2602
Christensen, F. E.0000-0001-5679-1946
Farrah, D.0000-0003-1748-2010
Harrison, F. A.0000-0003-2992-8024
Koss, M. J.0000-0002-7998-9581
LaMassa, S. M.0000-0002-5907-3330
Ricci, C.0000-0001-5231-2645
Stern, D.0000-0003-2686-9241
Zhang, W.0000-0002-1426-9698
Additional Information:© 2017 The American Astronomical Society. Received 2016 July 27; revised 2016 December 20; accepted 2016 December 27; published 2017 February 17. We thank the anonymous referee for useful comments which have helped to improve the paper. We acknowledge financial support from Majlis Amanah Rakyat (MARA) Malaysia (A.A.), the Science and Technology Facilities Council (STFC) grant ST/L00075X/1 (D.M.A.), ST/J003697/1 (P.G.), and ST/K501979/1 (G.B.L.). F.E.B. acknowledges support from CONICYT-Chile (Basal-CATA PFB-06/2007, FONDECYT Regular 1141218, "EMBIGGEN" Anillo ACT1101), and the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. P.B. would like to thank the STFC for funding. S.M.L.'s research was supported by an appointment to the NASA Postdoctoral Program at the NASA Goddard Space Flight Center, administered by the Universities Space Research Association under contract with NASA. M.K. acknowledges support from the Swiss National Science Foundation and Ambizione fellowship grant PZ00P2_154799/1. We acknowledge financial support from the CONICYT-Chile grants "EMBIGGEN" Anillo ACT1101 (C.R.), FONDECYT 1141218 (C.R.), Basal-CATA PFB–06/2007 (C.R.) and from the China-CONICYT fund (C.R.). NuSTAR is a project led by the California Institute of Technology (Caltech), managed by the Jet Propulsion Laboratory (JPL), and funded by the National Aeronautics and Space Administration (NASA). We thank the NuSTAR Operations, Software and Calibrations teams for support with these observations. This research has made use of the NuSTAR Data Analysis Software (nustardas) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). This research also made use of the data obtained through the High Energy Astrophysics Science Archive Research Center (HEASARC) Online Service, provided by the NASA/Goddard Space Flight Center, and the NASA/IPAC extragalactic Database (NED) operated by JPL, Caltech under contract with NASA. Facilities: Chandra - , Gemini:South - , NTT - , NuSTAR.
Group:NuSTAR, Space Radiation Laboratory, Astronomy Department
Funding AgencyGrant Number
Majlis Amanah Rakyat (MARA)UNSPECIFIED
Science and Technology Facilities Council (STFC)ST/L00075X/1
Science and Technology Facilities Council (STFC)ST/J003697/1
Science and Technology Facilities Council (STFC)ST/K501979/1
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)Basal-CATA PFB-06/2007
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1141218
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)Anillo ACT1101
Ministry of Economy, Development, and Tourism's Millennium Science InitiativeIC120009
NASA Postdoctoral ProgramUNSPECIFIED
Swiss National Science Foundation (SNSF)PZ00P2_154799/1
Subject Keywords:galaxies: active – galaxies: nuclei – techniques: spectroscopic – X-rays: galaxies – X-rays: individual (NGC 1448)
Issue or Number:2
Record Number:CaltechAUTHORS:20170222-080503232
Persistent URL:
Official Citation:A. Annuar et al 2017 ApJ 836 165
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:74450
Deposited By: Tony Diaz
Deposited On:22 Feb 2017 17:16
Last Modified:15 Nov 2019 05:00

Repository Staff Only: item control page