Transient obscuration event captured in NGC 3227
Astronomy and Astrophysics, vol. 652, pp. A150
Abstract
From Swift monitoring of a sample of active galactic nuclei (AGN) we found a transient X-ray obscuration event in Seyfert-1 galaxy NGC 3227, and thus triggered our joint XMM-Newton, NuSTAR, and Hubble Space Telescope (HST) observations to study this event. Here in the first paper of our series we present the broadband continuum modelling of the spectral energy distribution for NGC 3227, extending from near infrared (NIR) to hard X-rays. We use our new spectra taken with XMM-Newton, NuSTAR, and the HST Cosmic Origins Spectrograph in 2019, together with archival unobscured XMM-Newton, NuSTAR, and HST Space Telescope Imaging Spectrograph data, in order to disentangle various spectral components of NGC 3227 and recover the underlying continuum. We find the observed NIR-optical-UV continuum is explained well by an accretion disk blackbody component (Tmax = 10 eV), which is internally reddened by E(B − V) = 0.45 with a Small Magellanic Cloud extinction law. We derive the inner radius (12 Rg) and the accretion rate (0.1 M⊙ yr−1) of the disk by modelling the thermal disk emission. The internal reddening in NGC 3227 is most likely associated with outflows from the dusty AGN torus. In addition, an unreddened continuum component is also evident, which likely arises from scattered radiation, associated with the extended narrow-line region of NGC 3227. The extreme ultraviolet continuum, and the ‘soft X-ray excess’, can be explained with a ‘warm Comptonisation’ component. The hard X-rays are consistent with a power-law and a neutral reflection component. The intrinsic bolometric luminosity of the AGN in NGC 3227 is about 2.2 × 1043 erg s−1 in 2019, corresponding to 3% Eddington luminosity. Our continuum modelling of the new triggered data of NGC 3227 requires the presence of a new obscuring gas with column density NH = 5 × 1022 cm−2, partially covering the X-ray source (Cf = 0.6).
Authors 23
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Space Telescope Science Institute · Space Research Organisation Netherlands
Affiliation as printed
SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
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Space Telescope Science Institute
Affiliation as printed
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
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Leiden University · Leiden Observatory · Space Research Organisation Netherlands
Affiliation as printed
Leiden Observatory, Leiden University, PO Box 9513 2300 RA Leiden, The Netherlands
SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
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University of Strathclyde · Space Research Organisation Netherlands
Affiliation as printed
Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK
SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
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Space Research Organisation Netherlands · University of Amsterdam
Affiliation as printed
Anton Pannekoek Institute, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam, The Netherlands
SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
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Affiliation as printed
Department of Physics, Virginia Tech, Blacksburg VA 24061, USA
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Technion – Israel Institute of Technology
Affiliation as printed
Department of Physics, Technion-Israel Institute of Technology, 32000 Haifa, Israel
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Affiliation as printed
Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
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Affiliation as printed
Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
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Affiliation as printed
Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071, USA
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National Institute for Astrophysics
Affiliation as printed
INAF-IASF Bologna, Via Gobetti 101, 40129 Bologna, Italy
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Universitat Politècnica de Catalunya
Affiliation as printed
Departament de Física, EEBE, Universitat Politécnica de Catalunya, Av. Eduard Maristany 16, 08019 Barcelona, Spain
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Affiliation as printed
Italian Space Agency (ASI), Via del Politecnico snc, 00133 Roma, Italy
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European Space Agency · European Space Astronomy Centre
Affiliation as printed
Telespazio Vega UK for the European Space Agency (ESA), European Space Astronomy Centre (ESAC), Camino Bajo del Castillo, s/n, 28692 Villanueva de la Cañada, Madrid, Spain
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Affiliation as printed
Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
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Affiliation as printed
School of Physics and Astronomy and Wise Observatory, Tel Aviv University, Tel Aviv 69978, Israel
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Affiliation as printed
Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
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Affiliation as printed
Department of Astronomy, University of Geneva, 16 Ch. d’Ecogia, 1290 Versoix, Switzerland
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Centre National de la Recherche Scientifique · Institut de Planétologie et d'Astrophysique de Grenoble · Université Grenoble Alpes
Affiliation as printed
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
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National Institute for Astrophysics
Affiliation as printed
INAF-IASF Palermo, Via U. La Malfa 153, 90146 Palermo, Italy
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Brera Astronomical Observatory · Max Planck Institute for Extraterrestrial Physics
Affiliation as printed
INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy
Max Planck Institute fur Extraterrestriche Physik, 85748 Garching, Germany
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National Institute for Astrophysics
Affiliation as printed
INAF-IASF Bologna, Via Gobetti 101, 40129 Bologna, Italy
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Affiliation as printed
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
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