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Anatomy of the AGN in NGC 5548. VIII. XMM-Newton's EPIC detailed view of an unexpected variable multilayer absorber

Cappi, M. and De Marco, B. and Ponti, G. and Ursini, F. and Petrucci, P.-O. and Bianchi, S. and Kaastra, J. S. and Kriss, G. A. and Mehdipour, M. and Whewell, M. and Arav, N. and Behar, E. and Boissay, R. and Branduardi-Raymont, G. and Costantini, E. and Ebrero, J. and di Gesu, L. and Harrison, F. A. and Kaspi, S. and Matt, G. and Paltani, S. and Peterson, B. M. and Steenbrugge, K. C. and Walton, D. J. (2016) Anatomy of the AGN in NGC 5548. VIII. XMM-Newton's EPIC detailed view of an unexpected variable multilayer absorber. Astronomy and Astrophysics, 592 . Art. No. A27. ISSN 0004-6361.

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In 2013, we conducted a large multi-wavelength campaign on the archetypical Seyfert 1 galaxy NGC 5548. Unexpectedly, this usually unobscured source appeared strongly absorbed in the soft X-rays during the entire campaign, and signatures of new and strong outflows were present in the almost simultaneous UV HST/COS data. Here we carry out a comprehensive spectral analysis of all available XMM-Newton observations of NGC 5548 (precisely 14 observations from our campaign plus three from the archive, for a total of ~763 ks) in combination with three simultaneous NuSTAR observations. We obtain a best-fit underlying continuum model composed by i) a weakly varying flat (Γ ~ 1.5-1.7) power-law component; ii) a constant, cold reflection (FeK + continuum) component; iii) a soft excess, possibly owing to thermal Comptonization; and iv) a constant, ionized scattered emission-line dominated component. Our main findings are that, during the 2013 campaign, the first three of these components appear to be partially covered by a heavy and variable obscurer that is located along the line of sight (LOS), which is consistent with a multilayer of cold and mildly ionized gas. We characterize in detail the short timescale (mostly ~ks-to-days) spectral variability of this new obscurer, and find it is mostly due to a combination of column density and covering factor variations, on top of intrinsic power-law (flux and slope) variations. In addition, our best-fit spectrum is left with several (but marginal) absorption features at rest-frame energies ~6.7-6.9 keV and ~8 keV, aswell as a weak broad emission line feature redwards of the 6.4 keV emission line. These could indicate a more complex underlying model, e.g. a P-Cygni-type emission profile if we allow for a large velocity and wide-angle outflow. These findings are consistent with a picture where the obscurer represents the manifestation along the LOS of a multilayer of gas, which is also in multiphase, and which is likely outflowing at high speed, and simultaneously producing heavy obscuration and scattering in the X-rays, as well as broad absorption features in the UV.

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URLURL TypeDescription Paper
Harrison, F. A.0000-0003-2992-8024
Walton, D. J.0000-0001-5819-3552
Additional Information:© ESO, 2016. Received: 9 March 2016. Accepted: 5 April 2016. This paper is based on observations obtained with the XMM-Newton satellite, an ESA funded mission with contributions by ESA Member States and USA. M.C. and S.B. acknowledges financial support from the Italian Space Agency under grant ASI-INAF I/037/12/P1. G.P. acknowledges support via an EU Marie Curie Intra-European fellowship under contract no. FP-PEOPLE-2012-IEF- 331095. This work is based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and the USA (NASA). This research has made use of data obtained with the NuSTAR mission, a project led by the California Institute of Technology (Caltech), managed by the Jet Propulsion Laboratory (JPL) and funded by NASA. We thank the International Space Science Institute (ISSI) in Bern for their support and hospitality. SRON is supported financially by NWO, the Netherlands Organization for Scientific Research. M.M. acknowledges support from NWO and the UK STFC. This work was supported by NASA through grants for HST program number 13184 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, incorporated under NASA contract NAS5-26555. M.C. acknowledges financial support from contracts ASI/INAF n.I/037/12/0 and PRIN INAF 2011 and 2012. P.-O.P. acknowledges financial support from the CNES and from the CNRS/PICS. K.C.S. acknowledges financial support from the Fondo Fortalecimiento de la Productividad Científica VRIDT 2013. E.B. received funding from the EU Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 655324, and from the iCORE program of the Planning and Budgeting Committee (grant No. 1937/12). S.B., G.M., and A.D.R. acknowledge INAF/PICS financial support. G.M. and F.U. acknowledge financial support from the Italian Space Agency under grant ASI/INAF I/037/12/0-011/13. B.M.P. acknowledges support from the US NSF through grant AST-1008882. G.P. acknowledges support via an EU Marie Curie Intra-European fellowship under contract No. FP-PEOPLE-2012- IEF-331095 and Bundesministerium für Wirtschaft und Technologie/Deutsches Zentrum für Luft- und Raumfahrt (BMWI/DLR, FKZ 50 OR 1408). F.U. acknowledges Ph.D. funding from the VINCI program of the French-Italian University. M.W. acknowledges the support of a Ph.D. studentship awarded by the UK STFC.
Group:Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Agenzia Spaziale Italiana (ASI)ASI-INAF I/037/12/P1
Marie Curie FellowshipFP-PEOPLE-2012-IEF-331095
Agenzia Spaziale Italiana (ASI)ASI/INAF n.I/037/12/0
Istituto Nazionale di Astrofisica (INAF)PRIN INAF 2011
Istituto Nazionale di Astrofisica (INAF)PRIN INAF 2012
Centre National de la Recherche Scientifique (CNRS)CNRS-PICS
Fondo Fortalecimiento de la Productividad CientficaVRIDT 2013
European Research Council (ERC)655324
Israeli Committee for Planning and Budgeting1937/12
Agenzia Spaziale Italiana (ASI)ASI/INAF I/037/12/0-011/13
French-Italian University VINCI programUNSPECIFIED
Bundesministerium für Wirtschaft und Energie (BMWi)BMWI/DLR, FKZ 50 OR 1408
Deutsches Zentrum für Luft- und Raumfahrt (DLR)UNSPECIFIED
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Le Projet International de Coopération Scientifique (PICS)UNSPECIFIED
Subject Keywords:galaxies: active, X-rays: galaxies, galaxies: individual: NGC 5548
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2016-46
Record Number:CaltechAUTHORS:20160810-091225763
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Official Citation:Anatomy of the AGN in NGC 5548 - VIII. XMM-Newton’s EPIC detailed view of an unexpected variable multilayer absorber M. Cappi, B. De Marco, G. Ponti, F. Ursini, P.-O. Petrucci, S. Bianchi, J. S. Kaastra, G. A. Kriss, M. Mehdipour, M. Whewell, N. Arav, E. Behar, R. Boissay, G. Branduardi-Raymont, E. Costantini, J. Ebrero, L. Di Gesu, F. A. Harrison, S. Kaspi, G. Matt, S. Paltani, B. M. Peterson, K. C. Steenbrugge and D. J. Walton A&A, 592 (2016) A27 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69533
Deposited By: Deborah Miles
Deposited On:10 Aug 2016 18:38
Last Modified:30 Nov 2017 17:37

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