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NuSTAR Observations of the Compton-thick Active Galactic Nucleus and Ultraluminous X-ray Source Candidate in NGC 5643

Annuar, A. and Gandhi, P. and Alexander, D. M. and Lansbury, G. B. and Arévalo, P. and Ballantyne, D. R. and Baloković, M. and Bauer, F. E. and Boggs, S. E. and Brandt, W. N. and Brightman, M. and Christensen, F. E. and Craig, W. W. and Del Moro, A. and Hailey, C. J. and Harrison, F. A. and Hickox, R. C. and Matt, G. and Puccetti, S. and Ricci, C. and Rigby, J. R. and Stern, D. and Walton, D. J. and Zappacosta, L. and Zhang, W. (2015) NuSTAR Observations of the Compton-thick Active Galactic Nucleus and Ultraluminous X-ray Source Candidate in NGC 5643. Astrophysical Journal, 815 (1). Art. No. 36. ISSN 0004-637X.

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We present two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton, and Swift-BAT, we perform a high-quality broadband spectral analysis of the AGN over two decades in energy (~0.5–100 keV). Previous X-ray observations suggested that the AGN is obscured by a Compton-thick (CT) column of obscuring gas along our line of sight. However, the lack of high-quality ≳10 keV observations, together with the presence of a nearby X-ray luminous source, NGC 5643 X–1, have left significant uncertainties in the characterization of the nuclear spectrum. NuSTAR now enables the AGN and NGC 5643 X–1 to be separately resolved above 10 keV for the first time and allows a direct measurement of the absorbing column density toward the nucleus. The new data show that the nucleus is indeed obscured by a CT column of N_H ≳ 5 × 10^(24) cm^(−2). The range of 2–10 keV absorption-corrected luminosity inferred from the best-fitting models is L_(2–10,int) = (0.8–1.7) × 10^(42) erg s^(−1), consistent with that predicted from multiwavelength intrinsic luminosity indicators. In addition, we also study the NuSTAR data for NGC 5643 X–1 and show that it exhibits evidence of a spectral cutoff at energy E ~ 10 keV, similar to that seen in other ULXs observed by NuSTAR. Along with the evidence for significant X-ray luminosity variations in the 3–8 keV band from 2003 to 2014, our results further strengthen the ULX classification of NGC 5643 X–1.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Annuar, A.0000-0003-0387-1429
Gandhi, P.0000-0003-3105-2615
Alexander, D. M.0000-0002-5896-6313
Lansbury, G. B.0000-0002-5328-9827
Ballantyne, D. R.0000-0001-8128-6976
Baloković, M.0000-0003-0476-6647
Bauer, F. E.0000-0002-8686-8737
Boggs, S. E.0000-0001-9567-4224
Brandt, W. N.0000-0002-0167-2453
Brightman, M.0000-0002-8147-2602
Christensen, F. E.0000-0001-5679-1946
Harrison, F. A.0000-0003-2992-8024
Hickox, R. C.0000-0003-1468-9526
Matt, G.0000-0002-2152-0916
Puccetti, S.0000-0002-2734-7835
Ricci, C.0000-0001-5231-2645
Rigby, J. R.0000-0002-7627-6551
Stern, D.0000-0003-2686-9241
Walton, D. J.0000-0001-5819-3552
Zappacosta, L.0000-0002-4205-6884
Zhang, W.0000-0002-1426-9698
Additional Information:© 2015 The American Astronomical Society. Received 2015 June 2; accepted 2015 October 4; published 2015 December 4. The authors thank the anonymous referee for useful comments that have helped to improve the paper. We thank Chris Done for some discussions on the residuals around the iron line complex. A.A. thanks Wasutep Luangtip for useful discussion on NGC 5643 X–1 and help with the MARX simulation. We also thank Neil Gehrels and the Swift team for the simultaneous Swift-XRT observation. We acknowledge financial support from Majlis Amanah Rakyat (MARA) Malaysia (A.A.), the Science and Technology Facilities Council (STFC) grants ST/J003697/1 (P.G.), ST/I0015731/1 (D.M.A. and A.D.M.), and ST/K501979/1 (G.B.L.), the Leverhulme Trust (D.M.A.), NASA Headquarters under the NASA Earth and Space Science Fellowship Program grant NNX14AQ07H (M.B.), CONICYT-Chile grants Basal-CATA PFB-06/2007 (F.E.B.), FONDECYT 1141218 (F.E.B.), and "EMBIGGEN" Anillo ACT1101 (F.E.B.); the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS (F.E.B.). 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), and the XRT Data Analysis Software (xrt-das). 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: NuSTAR - The NuSTAR (Nuclear Spectroscopic Telescope Array) mission, XMM - Newton X-Ray Multimirror Mission satellite, CXO - , Swift - Swift Gamma-Ray Burst Mission.
Group:NuSTAR, Infrared Processing and Analysis Center (IPAC), Space Radiation Laboratory
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)ST/J003697/1
Science and Technology Facilities Council (STFC)ST/I0015731/1
Science and Technology Facilities Council (STFC)ST/K501979/1
NASA Earth and Space Science FellowshipNNX14AQ07H
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1141218
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)Anillo ACT1101
Iniciativa Científica Milenio del Ministerio de Economía, Fomento y TurismoIC120009
Subject Keywords:galaxies: active; galaxies: nuclei; techniques: spectroscopic; X-rays: galaxies; X-rays: individual (NGC 5643, NGC 5643 X–1)
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2015-17
Issue or Number:1
Record Number:CaltechAUTHORS:20160115-121320570
Persistent URL:
Official Citation:A. Annuar et al 2015 ApJ 815 36
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63713
Deposited By: Ruth Sustaita
Deposited On:15 Jan 2016 20:38
Last Modified:09 Mar 2020 13:19

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