Transient obscuration event captured in NGC 3227
Astronomy and Astrophysics, vol. 657, pp. A77
Abstract
The relationship between warm absorber (WA) outflows of active galactic nuclei and nuclear obscuration activities caused by optically thick clouds (obscurers) crossing the line of sight is still unclear. NGC 3227 is a suitable target for studying the properties of both WAs and obscurers because it matches the following selection criteria: WAs in both ultraviolet (UV) and X-rays, suitably variable, bright in UV and X-rays, and adequate archival spectra for making comparisons with the obscured spectra. In the aim of investigating WAs and obscurers of NGC 3227 in detail, we used a broadband spectral-energy-distribution model that is built in findings of the first paper in our series together with the photoionization code of SPEX software to fit the archival observational data taken by XMM-Newton and NuSTAR in 2006 and 2016. Using unobscured observations, we find four WA components with different ionization states (log ξ [erg cm s−1] ∼ −1.0, 2.0, 2.5, 3.0). The highest-ionization WA component has a much higher hydrogen column density (∼1022 cm−2) than the other three components (∼1021 cm−2). The outflow velocities of these WAs range from 100 to 1300 km s−1, and show a positive correlation with the ionization parameter. These WA components are estimated to be distributed from the outer region of the broad line region (BLR) to the narrow line region. It is worth noting that we find an X-ray obscuration event in the beginning of the 2006 observation, which was missed by previous studies. We find that it can be explained by a single obscurer component. We also study the previously published obscuration event captured in one observation in 2016, which needs two obscurer components to fit the spectrum. A high-ionization obscurer component (log ξ ∼ 2.80; covering factor Cf ∼ 30%) only appears in the 2016 observation, which has a high column density (∼1023 cm−2). A low-ionization obscurer component (log ξ ∼ 1.0 − 1.9; Cf ∼ 20%−50%) exists in both 2006 and 2016 observations, which has a lower column density (∼1022 cm−2). These obscurer components are estimated to reside within the BLR by their crossing time of transverse motions. The obscurers of NGC 3227 are closer to the center and have larger number densities than the WAs, which indicate that the WAs and obscurers might have different origins.
Authors 20
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Leiden University · University of Science and Technology of China · Chinese Academy of Sciences · Leiden Observatory · Space Research Organisation Netherlands · Nanjing University
Affiliation as printed
CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei 230026, PR China
Department of Astronomy, Nanjing University, Nanjing 210093, PR China
Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, PR China
Leiden Observatory, Leiden University, Niels Bohrweg 2, 2300 RA Leiden, The Netherlands
SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands
School of Astronomy and Space Science, University of Science and Technology of China, Hefei 230026, PR China
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Leiden University · Leiden Observatory · Space Research Organisation Netherlands
Affiliation as printed
Leiden Observatory, Leiden University, Niels Bohrweg 2, 2300 RA Leiden, The Netherlands
SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands
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Space Telescope Science Institute · Space Research Organisation Netherlands
Affiliation as printed
SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
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Hiroshima University · University of Strathclyde · Space Research Organisation Netherlands
Affiliation as printed
Department of Physical, Hiroshima University, 1-3-1 Kagamiyama, HigashiHiroshima, Hiroshima 739-8526, Japan
Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK
SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands
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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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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-Institut für Extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
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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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Universitat Politècnica de Catalunya
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Departament de Física, EEBE, Universitat Politècnica de Catalunya, Av. Eduard Maristany 16, 08019 Barcelona, 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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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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European Space Agency · European Space Astronomy Centre
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Telespazio 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
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, 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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University of Science and Technology of China · Chinese Academy of Sciences
Affiliation as printed
CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei 230026, PR China
School of Astronomy and Space Science, University of Science and Technology of China, Hefei 230026, PR China
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Affiliation as printed
Department of Astronomy, University of Geneva, 16 Ch. d’Ecogia, 1290 Versoix, Switzerland
Department of Astronomy, University of Geneva, 16 Ch. d'Ecogia, 1290 Versoix, Switzerland
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Affiliation as printed
Italian Space Agency (ASI), Via del Politecnico snc, 00133 Roma, Italy
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University of Science and Technology of China · Chinese Academy of Sciences
Affiliation as printed
CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei 230026, PR China
School of Astronomy and Space Science, University of Science and Technology of China, Hefei 230026, PR China
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